Tuning Logic of Imidazole Heteroaromatic Building Blocks: How Dual Nitrogen Sites and Substitution / Salt Forms / Ring Fusion Modulate Charge, Hydrogen Bonding, and Coordination (with Tables A–E)
1.Real-World Problem: Why Can the Same Molecule Behave Very Differently with pH or Metal Ions?
In drug molecules, catalytic systems, separation/purification, and materials media, R&D often encounters a recurring challenge: the same molecule shows dramatically different behavior under different conditions, making results difficult to reproduce. Typical triggers fall into three main categories:
1. Small changes in pH can shift the distribution of ionic states (especially when pH is close to the key site’s pKa), which in turn affects solubility, adsorption/binding strength, and reaction rate.
2. Metal ions in the system (transition metals such as Fe/Cu/Zn/Ni—even at trace levels) may coordinate/chelate with the molecule, generating new structural states and reaction pathways.
3. Different substituents or different salt forms / counterions on the same core scaffold can change charge distribution and solvation, making an originally broad “effective window” much more sensitive.
A key reason imidazole-type heteroaromatic building blocks have remained high-frequency motifs for decades is this: a small, clearly defined aromatic five-membered ring concentrates these differences into a few core, comparable factors—charge state (acid–base), hydrogen-bond networks, and metal-coordination ability—making systematic comparison and targeted tuning easier.
2.Basic Concepts: What Are “Heteroaromatic Building Blocks—Imidazole Family”?
2.1 Heteroaromatic building blocks
Here, a “building block” refers to a ring module that can be repeatedly used in molecular design. It can be used to build scaffolds, tune polarity and electronic effects, provide key interaction sites, and support series-based iteration (clear structural controls; property changes are easier to interpret). Emphasizing “building block” highlights that it is more like a standardized, reusable modular interface, rather than a one-off intermediate or a temporary functional group.
2.2 Imidazole and the imidazole family
1. Imidazole: an aromatic five-membered heterocycle with two nitrogens (a 1,3-diaza ring). It exhibits 1H/3H tautomerism, and is commonly described using 1H-imidazole as the main representation. In any given tautomer, it presents a combination of one pyridine-like N (primarily a hydrogen-bond acceptor; more often involved in coordination; more readily protonated) plus one pyrrole-like N–H (linked to aromaticity; more often acting as a hydrogen-bond donor).
For unsubstituted imidazole, tautomerism interconverts the two forms, so the “pyridine-like / pyrrole-like roles” of the two nitrogens are interchangeable on average (not permanently fixed on the same nitrogen). Imidazole and its protonated form imidazolium form a conjugate acid–base pair.
2. Imidazole family: a group of structure types centered on the imidazole ring that are most often treated as reusable building blocks in R&D. Common examples include:
a) Imidazole core and substituted imidazoles (for tuning acid–base properties, hydrogen bonding, and the solubility/salt-form window);
b) Fused-ring derivatives (e.g., benzimidazole, often used as medicinal chemistry scaffold platforms);
c) Imidazolium salts (stable ionic forms, often used as an “ionic-state entry / precursor”);
d) N-heterocyclic carbene (NHC) ligand systems derived from imidazolium salts (carbenes generated by deprotonation at the key carbon, used to build coordination and catalytic systems).
2.3 A common natural reference: the imidazole side chain of histidine
Histidine’s side chain contains an imidazole ring. Literature often gives an “empirical range”: the pKa of the imidazole side chain is frequently around ~6. This means that within a pH window such as 5.5–6.5, it more readily displays switchable charge states (protonated/deprotonated), thereby providing some buffering capacity while strongly influencing hydrogen bonding, electrostatics, and metal coordination.
Additional note: this pKa is not a fixed constant—it can shift with microenvironment (ionic strength, nearby charges, local structure/hydrophobicity, etc.). Even so, “near physiological pH and readily switching between two states” remains one important reason imidazole is used so frequently in biological systems.
3.Structural Features: Four Key “Property Switches” of Imidazole
The “information density” of imidazole comes from the non-equivalence of its two nitrogens:
1. Pyrrole-like N–H: its lone pair participates in aromaticity; it behaves more as a hydrogen-bond donor.
2. Pyridine-like N: its lone pair does not participate in aromaticity; it is the primary hydrogen-bond acceptor and more often serves as a metal-coordination site.
Together with tautomerism (N–H position switching), protonation / salt formation (imidazolium), and the very common ring-fusion expansion (benzimidazole, etc.), most experimentally observed property changes can be explained with the following four “switches”:
Structural switch (what is changed) | What it changes (core reason) | Common observable outcomes |
Division of labor between the two nitrogens (N–H vs N:) | In the neutral state, it often appears as “one N–H donor + one N acceptor”; the nitrogen bearing a lone pair (pyridine-like N) more often participates in metal coordination and is more readily protonated. | Richer H-bond/binding modes; more sensitive to solvent, salts, and metal ions; the same scaffold shows larger differences across different systems. |
Tautomerism (N–H migrates between the two nitrogens) | Donor/acceptor positions can switch; electron distribution and H-bond geometry change accordingly. | More than one interaction/binding orientation may exist; behavior can be “less single-state” (e.g., broadened spectra / multiple sets of signals; multimodal binding data). |
Protonation / salt formation (imidazole → imidazolium) | Charge state strongly changes polarity and ionic interactions; H-bond acceptor ability is markedly weakened or lost. | Clear “switch-like” changes in solubility, partitioning/adsorption, and interfacial behavior; more sensitive to counterion and ionic strength. |
Ring fusion expansion (e.g., benzimidazole) | Increased rigidity and π-system size; higher contribution of hydrophobic and π–π interactions; often accompanied by shifts in acid–base behavior and solubility window. | Better suited for series-based comparisons (affinity/selectivity trends more comparable); but may reduce solubility or increase nonspecific adsorption; metabolic/chemical stability trends often shift with scaffold rigidity. |
4.Practical Classification of the Imidazole Family: What You Change → What Shifts → Why It’s Commonly Used
Category | Typical structural modification | Main properties being tuned | Common use cases |
A. Core / lightly substituted imidazoles (baseline controls) | Unsubstituted or minimally substituted; closest to “origin behavior” | Baseline of acid–base behavior + H-bond donor/acceptor pattern + coordination ability | Most direct system baseline/control; quickly tests whether “imidazole fits this system.” |
B. N-substituted imidazoles (remove N–H, reduce multi-state behavior) | Alkyl/aryl substitution at N (reduces or eliminates N–H) | Tautomerism greatly reduced; H-bond donor ability decreases/disappears; protonation, salt formation, and solubility behavior shift accordingly | More single-state and easier to reproduce; preferred when N–H would introduce extra H-bonds/multiple forms; also used as a more controllable coordination/polarity module. |
C. C-substituted imidazoles (2/4/5 fine-tuning and “handles”) | Substituents or linkers introduced at 2/4/5 positions | Integrated tuning of electronic effects + sterics + polarity/hydrophobicity; often affects pKa, solubility, and the spatial position/orientation of interactions (H-bond angles, coordination geometry, etc.) | Fine-tuning binding strength/selectivity; the 2-position is often used as a “linking handle” for series-based controls (turning substituent changes into a controllable SAR gradient). |
D. Ring fusion expansion: benzimidazoles, etc. (more rigid, more π-biased) | Fusion of imidazole with an aromatic ring; expanded π system and greater rigidity | Rigidity ↑; weight of π/hydrophobic interactions ↑; often accompanied by shifts in acid–base and solubility windows | Often discussed as drug scaffolds/fragment platforms: facilitates series-based comparisons and property transfer; requires attention to solubility vs nonspecific adsorption trade-offs. |
E. Ionic state: imidazolium salts (charge-state switch) | Positively charged imidazolium with different counterions | Ionic interactions, dielectric/solvation, and interfacial behavior change markedly; counterion effects are often large | Common in ionic liquids/electrolytes and functional materials; key entry point for NHC precursors; more direct when a “positively charged model” or strong ionic interactions are needed. |
5.Three Application Mainlines
Application mainline | Structural categories mainly used (corresponding to Part 4 A–E) | Key benefits brought by structural change | What to prioritize measuring |
Drugs / bioactive molecules | H-bond donors/acceptors + a tunable protonation window (mainly A/C/D) | The same scaffold can turn “H-bond geometry, polarity, and charge state” into iteratable SAR variables via substitution / ring fusion | Whether the binding mode is stable; salt form / solubility window; activity/selectivity trends driven by substitution position changes |
IMAC purification (His-tag) | Coordination competition (A is the most typical) | Turns “metal coordination” from a nuisance into a process knob: imidazole competes with immobilized metal sites, enabling controllable wash/elution windows | In washing: whether nonspecific binding decreases; in elution: whether the target elutes cleaner/more concentrated; process signals such as metal leaching and protein recovery yield |
Catalysis and functional media | Ionic state / imidazolium (E) and derivatives | Imidazolium is both a common entry point to NHC (N-heterocyclic carbene) precursors and a modular unit for “tunable media” (ionic liquids/electrolytes); structure and anion/cation pairing directly determine system properties | In catalysis: mapping activity/selectivity to ligand electronics/sterics; in media: viscosity/polarity/solubility/phase behavior responses to cation–anion combinations |
Application Quick Reference: Three Most Typical “Structure → Use” Implementation Paths
1. Drugs / bioactive molecules (e.g., benzimidazoles)
a) Use the same scaffold to couple H-bond donor/acceptor features with a protonation / salt-forming window, then perform series-based fine tuning through substitution / ring fusion.
b) How to use: treat binding mode + solubility/salt form + selectivity as an iteratable set of SAR variables for side-by-side comparison.
2. His-tag protein IMAC (Immobilized Metal Affinity Chromatography) purification
a) Exploit imidazole’s coordination competition: low concentrations for washing to reduce nonspecific adsorption; high concentrations for eluting the target protein.
b) How to use: treat imidazole concentration as a process knob; optimize the window around “wash background/purity—recovery—elution peak shape.”
3. Imidazolium salts (Category E): catalysis and functional media
a) As a charge-state platform, one end serves catalysis control as a common precursor entry to NHC ligands; the other end enables tunable media in ionic liquids/electrolytes via “cation substitution + anion/counterion selection.”
b) How to use: when strong ionic interactions or tunable medium properties are needed, prioritize selecting an “imidazolium platform” and treat the counterion as a key variable for side-by-side comparison. Also note that systems containing BF₄⁻/PF₆⁻ may undergo anion hydrolysis under aqueous or acidic conditions and introduce corrosion risk (HF). In electrolytes/surface treatment/aqueous systems, include water content / acidity and materials compatibility as explicit evaluation variables.
6.Product Navigation Table | Selection for “Imidazole / Benzimidazole Systems”: Quickly Locate Tables A–E by R&D Task
Your research task / experimental need | Recommended table to check first | Selection logic |
Gastric acid–related research / quality analysis: PPI reference standards (omeprazole/esomeprazole/lansoprazole/pantoprazole/rabeprazole) | Table A | Within one pharmacological family, “horizontal comparisons” are often needed (stability, impurity profile, salt form/polymorphs, method validation). Putting them in one table minimizes lookup cost. |
H2-receptor pharmacology / receptor binding & reference (cimetidine) | Table A | H2 antagonists and PPIs differ mechanistically, but both fall under “gastric acid–related drug reference” scenarios; Table A centralizes them for one-click locating. |
Anti-anaerobic / antiprotozoal: nitroimidazole API references (metronidazole/tinidazole/secnidazole/ornidazole) | Table B | Nitroimidazoles form a highly homologous compound group; commonly used for efficacy/tolerability/PK comparisons and analytical method development—fastest to search when centralized in Table B. |
Antifungal drug research / references / impurities & stability: azole antifungals (clotrimazole/miconazole/econazole/oxiconazole/bifonazole/tioconazole/ketoconazole/fluconazole nitrate) | Table C | Strong shared features (solubility/formulation window, methods, impurity profiles); within-table side-by-side comparison is most practical. |
Agrochemical fungicide activity / references / methods: benzimidazole fungicides (thiabendazole/carbendazim/benzimidazole carbamates) | Table C | Different from pharma azoles, but still a “fungal control” application set; Table C groups by use to enable quick locating and comparisons. |
“Imidazole / benzimidazole” heteroaromatic building blocks: need cores and substituted variants for structure controls | Table D | Focus is on “entry structures / derivatizable positions,” not pharmacology; Table D groups by building blocks and tools, matching synthesis-driven selection. |
Functionalization handles: 2-amino / 2-halo / arylation / nitro substitution (for subsequent coupling, substitution, or SAR expansion) | Table D | Value lies in “what structure you can modify next”; Table D centralizes these for selecting starting materials by reaction handle. |
MOF/ZIF materials: need 2-methylimidazole (2-MeIm) as a high-frequency ligand | Table D | 2-MeIm is frequently used in ZIF synthesis and should be located as a “materials ligand / foundational building block”; Table D is the most direct. |
Metal corrosion inhibition / anti-tarnish / metal-coordination additives: thio-imidazoles/benzimidazoles (2-mercaptoimidazole, 2-mercaptobenzimidazole, 2-mercapto-1-methylimidazole) | Table D | Core is N/S dual-site adsorption/coordination on metal surfaces; this is an engineering/material additive route and is centrally collected in Table D. |
Carboxylic acid → amide/ester/carbonate coupling: need CDI (N,N′-carbonyldiimidazole) | Table D | CDI is a classic “imidazole activation” coupling tool; it is categorized by reagent function in Table D for parallel screening vs similar activators. |
Sulfonylation / sulfonamide synthesis: need 1,1′-sulfonyldiimidazole | Table D | A sulfonylation activator; best retrieved as a “synthetic tool,” and Table D provides direct locating for route comparison. |
Dicarbonyl activation / route-development controls: need 1,1′-oxalyldiimidazole (oxalyl diimidazole) | Table D | Same “imidazole activation” concept as CDI but with a different reactivity window; Table D enables process window/side-reaction comparisons. |
Primary amine → organic azide diazotransfer: 1H-imidazole-1-sulfonyl azide hydrochloride | Table D | A typical diazotransfer reagent; selection prioritizes use case and controllability/safety boundaries. Evaluate and handle under organic azide safety norms; avoid treating it as a generic azide source. |
Ionic liquids as solvents/electrolytes/separation media: EMIM/BMIM + BF₄⁻/PF₆⁻/TFSI⁻/Cl⁻ | Table E | The main variables are “cation scaffold + anion switching”; Table E allows direct comparison of viscosity/polarity/phase behavior/electrochemical window by platform. |
Ionic liquid synthesis precursors / anion-exchange routes: imidazolium chloride salts such as EMIMCl, BMIMCl | Table E | Chloride salts are common ionic-liquid precursors (then swapped to BF₄⁻/PF₆⁻/TFSI⁻). Table E is organized by “precursor → platform,” matching the process pathway. |
NHC metal catalysis: bulky aryl imidazolium salts (Mes / IPr types) as NHC precursors | Table E | Focus is ligand sterics/electronics and catalytic stability; this is “ligand-precursor platform” selection, centralized in Table E for direct picking. |
Need N-alkyl imidazoles as bases / ligands / ionic-liquid precursors (1-ethyl/1-butyl, etc.) | Table E | These molecules often switch among three roles (base/ligand/ionic-liquid precursor); Table E unifies them to avoid fragmented lookup. |
Biochemistry / cell culture or physiological references: L-histidine, histamine | Table D | These are biological inputs/references and should not be mixed with drug APIs or ionic liquids; Table D groups them more clearly by “basic molecules and use.” |
Table A | Pharmaceutical APIs | Acid Suppression & Gastric Drugs (PPIs + H2)
Category | CAS No. | Aladdin Cat. No. | Name | Specification / Purity | Product features & applications |
Pharmaceutical API | PPI acid suppressant | 119141-88-7 | Esomeprazole | Moligand™, ≥99% | Representative proton pump inhibitor (PPI): used in gastric acid–related disease research; reference standard for impurity profiling and stability studies; suitable for “PPI series horizontal comparisons” (vs omeprazole, etc.) to evaluate how configuration/salt form affects properties. | |
Pharmaceutical API | PPI acid suppressant | 73590-58-6 | Omeprazole | Moligand™, ≥98% | Classic PPI reference: used for gastric acid drug research, reference standards, impurity profiling, and stability studies; also a representative case for “PPIs as acid-labile prodrugs,” highlighting formulation and storage considerations. | |
Pharmaceutical API | PPI acid suppressant | 103577-45-3 | Lansoprazole | Moligand™, ≥98% | PPI series member: used for drug research, reference standards, and stability/impurity studies; suitable for cross-comparison with omeprazole/pantoprazole/rabeprazole to link “structural differences → property/metabolism differences.” | |
Pharmaceutical API | PPI acid suppressant | 102625-70-7 | Pantoprazole | Moligand™, ≥97% | PPI series member: used for API research and analytical references; often used to compare PPIs in stability, salt form/polymorph behavior, and process windows. | |
Pharmaceutical API | PPI acid suppressant | 117976-89-3 | Rabeprazole | Moligand™, ≥97% | PPI series member: used for drug research, reference standards, and method/stability studies; suitable for comparative analysis of “fine structural tuning → PK/stability differences” vs other PPIs. | |
Pharmaceutical API | H2 receptor antagonist (imidazole-containing) | 51481-61-9 | Cimetidine | Moligand™, ≥99% | Classic H2 receptor antagonist: a representative receptor ligand containing an imidazole ring, used for pharmacology research, analytical references, and interaction studies; also commonly cited to discuss how imidazole basicity/coordination affects in vivo and in vitro behavior. |
Table B | Pharmaceutical APIs | Nitroimidazoles (Anti-anaerobic / Antiprotozoal)
Category | CAS No. | Aladdin Cat. No. | Name | Specification / Purity | Product features & applications |
Pharmaceutical API | Nitroimidazole (anti-anaerobic / antiprotozoal) | 443-48-1 | Metronidazole | UltraBio™, Ultra-pure grade | A representative nitroimidazole anti-anaerobic/antiprotozoal drug: used in drug research, analytical reference work, and impurity/degradation studies; the “nitroimidazole” motif is also a widely used representative in studies of anti-anaerobic activity and bioreductive mechanisms. | |
Pharmaceutical API | Nitroimidazole (anti-anaerobic / antiprotozoal) | 19387-91-8 | Tinidazole | Moligand™, ≥98% (HPLC) (T) | A representative nitroimidazole: used for API research and reference comparisons in anti-anaerobic/antiprotozoal applications; often compared with metronidazole as a reference set for “efficacy—tolerability—dosing” trade-offs. | |
Pharmaceutical API | Nitroimidazole (anti-anaerobic / antiprotozoal) | 3366-95-8 | Secnidazole | ≥98% | A representative nitroimidazole: used for drug research and reference standards; commonly considered alongside metronidazole/tinidazole/ornidazole for “within-class structural differences → course length / tolerability / pharmacokinetics” comparisons and for analytical method validation. | |
Pharmaceutical API | Nitroimidazole (anti-anaerobic / antiprotozoal) | 16773-42-5 | Ornidazole | ≥98% | A nitroimidazole API: used in anti-anaerobic/antiprotozoal research, reference standards, and quality analysis; also applicable to studies of nitro-reduction mechanisms and resistance. |
Table C | Pharmaceutical / Agrochemical | Azole Antifungals + Benzimidazole Fungicides
Category | CAS No. | Aladdin Cat. No. | Name | Specification / Purity | Product features & applications |
Pharmaceutical API | Azole antifungal (imidazole) | 65277-42-1 | Ketoconazole | Moligand™, ≥99% (EP, titration) | Broad-spectrum imidazole antifungal: used for API research, QC, and method validation; a representative example of the “azole ring–coordination” mechanism (inhibition of fungal CYP51), widely referenced in azole SAR and resistance studies. | |
Pharmaceutical API | Azole antifungal (imidazole) | 23593-75-1 | Clotrimazole | Moligand™, ≥98% (HPLC) | Classic imidazole antifungal: commonly used in topical formulation research, analytical references, and method development; also a representative case highlighting that many azoles are highly hydrophobic and require careful management of formulation/solubility windows. | |
Pharmaceutical API | Azole antifungal (imidazole) | 22916-47-8 | Miconazole | Moligand™, ≥98% | Imidazole antifungal: often used in topical/local formulation studies, reference standards, and quality analysis; also useful for studying common features of “azole–metalloenzyme target interactions.” | |
Pharmaceutical API | Azole antifungal (imidazole) | 27220-47-9 | Econazole | Moligand™, ≥97% | Imidazole antifungal: used for drug research, analytical references, and related formulation/impurity studies; commonly used as a reference sample in topical antifungal drug systems. | |
Pharmaceutical API | Azole antifungal (imidazole) | 60628-96-8 | Bifonazole | ≥98% (HPLC) | Topical imidazole antifungal: commonly used in formulation/solubility-window and quality-analysis studies; can serve as a reference sample for “highly hydrophobic azoles” in formulation and delivery-system comparisons. | |
Pharmaceutical API | Azole antifungal (imidazole) | 65899-73-2 | Tioconazole | ≥98% | Imidazole antifungal: used for API research, analytical references, and impurity/stability studies; since solubility and formulation-window management is a shared feature of azoles, it is suitable for method and formulation benchmarking. | |
Pharmaceutical API | Azole antifungal (imidazole) | 64211-45-6 | Oxiconazole | ≥97% | Topical imidazole antifungal: used for API research, analytical references, and formulation/stability studies; suitable for within-class comparisons with miconazole/econazole and related agents. | |
Pharmaceutical API | Azole antifungal (imidazole, salt form) | 61318-91-0 | Sulconazole nitrate | ≥95% | Salt-form azole antifungal: used for API/reference standards and analytical method development; salt forms may improve stability/handling or support formulation-window assessment, making it suitable as a “free base vs salt form” comparison sample. | |
Pesticide / fungicide | Benzimidazole class (fungal control) | 148-79-8 | Thiabendazole | ≥99% | Representative benzimidazole fungicide: used in agrochemical activity studies, reference standards, and method development; also a common sample for studying benzimidazole–fungal target interactions and resistance issues. | |
Pesticide / fungicide | Benzimidazole class (carbendazim) | 10605-21-7 | Carbendazim | ≥97% | Classic systemic benzimidazole fungicide: used for agrochemical activity research, reference standards, and method development; also a common representative in “activity—resistance” discussions of the benzimidazole class. | |
Pesticide / fungicide | Benzimidazole class (systemic fungicide) | 17804-35-2 | 1-Butylcarbamoyl-2-benzimidazolyl methylcarbamate | ≥97% | A benzimidazole carbamate-type fungicide structure: used for agrochemical activity/mechanism studies and analytical references; also used in impurity profiling, degradation studies, and method development. |
Table D | Core Scaffolds / Derivatives / Functional Monomers + Synthetic Reagents (Grouped by “Similar Structure and Use”)
Category | CAS No. | Aladdin Cat. No. | Name | Specification / Purity | Product features & applications |
Biochemical amino acid | Histidine platform (cell culture / coordination site) | 71-00-1 | L-Histidine | Animal-free, USP, Moligand™, European Pharmacopoeia (Ph. Eur.), for cell culture | A key amino acid bearing an imidazole side chain: commonly used nutrient component and reference in cell culture/biochemical systems; the imidazole site can participate in metal coordination and acid–base control, supporting protein/enzyme studies, metal-binding behavior investigations, and buffer-related experiments. | |
Biogenic amine | Histamine (receptor ligand / physiological activity reference) | 51-45-6 | Histamine | Moligand™, ≥96% | An endogenous biogenic amine containing an imidazole ring: commonly used in H1/H2 receptor pharmacology, allergy/inflammation model references, and method validation; also a classic example of how “imidazole basicity/protonation state” manifests in biological systems. | |
Core scaffold | Imidazole (general buffer / coordination / catalysis) | 288-32-4 | Imidazole | Anhydrous grade, ACS, ≥99% | Classic imidazole core: widely used for buffering and pH control (e.g., biochemical/protein systems), and as a competitive eluent in His-tag protein purification; also used as an N-donor ligand/intermediate and as a nucleophilic catalyst (acylation/condensation, etc.), serving as a starting point for many imidazole/imidazolium derivatives. | |
Salt form | Imidazole salt (acidified solubility / coordination & buffering) | 1467-16-9 | Imidazole hydrochloride | ≥98% | Salt-form control of imidazole: used to increase water solubility and establish systems with more controllable acidity/ionic strength; also commonly used to compare “free base vs salt form” in coordination/buffering-related experiments. | |
Core scaffold | Benzimidazole (heteroaromatic building block / coordination platform) | 51-17-2 | Benzimidazole (BZI) | AR, ≥98% (HPLC) | Classic benzimidazole core: widely used building block in drug and materials chemistry; can form salts to tune solubility; also serves as an N-donor coordination/H-bond scaffold for ligand design, functional materials, and building-block library construction. | |
Benzimidazole derivative | N-substituted building block / coordination & materials precursor | 1632-83-3 | 1-Methylbenzimidazole | ≥99% | An N-substituted benzimidazole building block: used for building-block libraries and further functionalization; also serves as an N-donor ligand/ion-pair model and as a starting point for metal coordination and materials-related studies. | |
Benzimidazole derivative | 2-methyl substitution (building block / coordination) | 615-15-6 | 2-Methylbenzimidazole | ≥98% | Common benzimidazole building block: for building salt-formable/coordination-capable fragment libraries; 2-substitution helps tune basicity, solubility, and H-bonding patterns, suitable for SAR/material control comparisons. | |
Biochemistry-related | 5,6-DBI (vitamin B12 lower-ligand fragment) | 582-60-5 | 5,6-Dimethylbenzimidazole (5,6-DBI) | ≥99% | Representative lower-ligand fragment in vitamin B12 (cobalamin) systems: used as a reference in biochemistry/enzymology and vitamin-related studies; also a commonly used fragment in benzimidazole building-block and coordination-chemistry research. | |
Benzimidazole derivative | Extended conjugated aryl (optoelectronics / ligand) | 716-79-0 | 2-Phenylbenzimidazole | ≥98% | A more conjugated arylated benzimidazole building block: often used in emissive/optoelectronic materials (e.g., fluorescent cores, electron-transport related structures) and in coordination systems; suitable as a “conjugation–rigidity” comparison fragment. | |
Benzimidazole derivative | Nitro substitution (electronic effects / mechanistic control) | 94-52-0 | 6-Nitrobenzimidazole | ≥98% | Strong electron-withdrawing nitro group for tuning electronics and acid–base behavior: commonly used as a mechanistic/electronic-effect control building block to compare “substituent → electronic/H-bonding/coordination” changes in medicinal and materials chemistry. | |
Benzimidazole derivative | 2-amino (building block / coordination / salt form) | 934-32-7 | 2-Aminobenzimidazole | ≥97% | The 2-amino group provides a further derivatization handle (acylation/sulfonylation/coupling, etc.), commonly used in medicinal building blocks and ligand design; can also form salts to tune solubility for structure–property comparisons. | |
Benzimidazole derivative | 2-halo (functionalization handle) | 4857-06-1 | 2-Chlorobenzimidazole | ≥97% | A high-frequency “reaction handle” at C-2: facilitates subsequent substitution/coupling to build benzimidazole derivative libraries; suitable for route development and rapid building-block expansion. | |
Benzimidazole derivative | 6-halo (regioselectivity control) | 4887-88-1 | 6-Bromo-1H-benzimidazole | ≥97% | Halogen on the aromatic ring enables further cross-coupling/substitution, providing a regioselective expansion entry; commonly used to build multi-substituted benzimidazole series for SAR/material comparisons. | |
Sulfur-containing benzimidazole | Metal corrosion inhibition / coordination & stabilizer | 583-39-1 | 2-Mercaptobenzimidazole | ≥98% | Benzimidazole + thiol site enhances metal binding: used for corrosion inhibition of copper and alloys, suppressing metal-ion side reactions in rubber/polymer systems, and stabilization exploration; also a typical N/S coordination scaffold. | |
Basic monomer | 2-Methylimidazole (ZIF/MOF ligand & base) | 693-98-1 | 2-Methylimidazole | ≥98% | High-frequency “2-MeIm” ligand: one of the most commonly used ligands in ZIF-type MOF synthesis (e.g., ZIF-8); also a general organic base/nucleophilic catalyst and curing accelerator, bridging materials and organic synthesis applications. | |
Substituted imidazole | 4-substitution (organic base / intermediate) | 822-36-6 | 4-Methylimidazole | ≥98% | A basic substituted imidazole feedstock: used for synthetic intermediates, coordination/salt construction, and basicity control; suitable for structural comparisons of how substitution position (2- vs 4-) impacts basicity and reactivity. | |
Substituted imidazole | C-2 alkyl (organic base / curing accelerator / ligand) | 1072-62-4 | 2-Ethylimidazole | ≥98% | Representative substituted imidazole base: commonly used as an accelerator in epoxy curing and latent-curing system studies; also used in nucleophilic catalysis and as a coordination/ionic-liquid precursor; C-2 substitution tunes basicity, volatility, and reactivity. | |
Substituted imidazole | C-2 alkyl (organic base / coordination & structural control) | 36947-68-9 | 2-Isopropylimidazole | ≥98% | Branched alkyl substitution at C-2: used to compare steric/hydrophobic effects on basicity, nucleophilicity, and catalytic/curing acceleration performance; also used as a ligand and as a precursor to ionic liquids or salts. | |
Substituted imidazole | Alkyl substitution (curing acceleration / basicity tuning) | 931-36-2 | 2-Ethyl-4-methylimidazole | ≥96% | Substituted imidazole base: commonly used in epoxy curing acceleration and polymerization systems to tune reaction rate and exotherm window; also useful as a structural control (multi-site substitution effects on basicity/sterics). | |
Substituted imidazole | C-2 aryl (high-melting ligand / emissive & materials building block) | 670-96-2 | 2-Phenylimidazole | ≥98% | Aryl substitution at C-2 increases conjugation and rigidity: often used in materials chemistry (e.g., coordination luminescence systems, H-bond crystal engineering) and ligand design; also serves as a building block intermediate in organic synthesis. | |
Functional monomer | Imidazole-containing carboxylic acid (polymer / coordination / buffering) | 104-98-3 | 4-Imidazoleacrylic acid | ≥98% | A carboxylic acid monomer with an imidazole side group: used in functional polymers (pH responsiveness, metal-ion binding, ionic conduction) and coordination crosslinking systems; the imidazole site provides protonation/coordination functions for materials modification and interfacial chemistry. | |
Sulfur-containing imidazole | Metal corrosion inhibition / coordination & thio-ligand | 872-35-5 | 2-Mercaptoimidazole | ≥98% | Contains dual N/S sites: strong adsorption/coordination toward metals such as Cu/Ag; commonly used for corrosion inhibition, anti-tarnish, and surface-treatment additives; also used as a thio-ligand fragment in coordination chemistry and functional materials research. | |
Functional additive | Metal corrosion inhibition / copper protection (thiol imidazole) | 60-56-0 | 2-Mercapto-1-methylimidazole | Moligand™, ≥98% | Strong adsorption/coordination on metal surfaces via S/N sites: commonly used as a corrosion inhibitor, anti-tarnish agent, or surface-treatment additive for copper/silver systems; also serves as a sulfur-containing imidazole building block in coordination/materials chemistry. | |
Synthetic reagent | Carbonyl activation / coupling (CDI) | 530-62-1 | N,N′-Carbonyldiimidazole (CDI) | ≥99% | Classic activator: converts carboxylic acids into acyl imidazole intermediates for forming amide/ester/carbonate bonds; controllable byproducts and convenient handling, often selected for “mild coupling” from small scale to scale-up routes. | |
Synthetic reagent | Sulfonylation activation / sulfonamide synthesis | 7189-69-7 | 1,1′-Sulfonyldiimidazole | ≥98% | Sulfonylation activator: converts sulfonic/sulfonyl substrates into more reactive intermediates to facilitate sulfonamide/sulfonate ester synthesis; widely used in making sulfonyl-functional drug and materials monomers. | |
Synthetic reagent | Dicarbonyl activation / coupling (oxalyl diimidazole) | 18637-83-7 | 1,1′-Oxalyldiimidazole | ≥95% | Dicarbonyl activation/transfer reagent: used for carboxylic acid derivatization, coupling, and building reactive intermediates; shares the “imidazole activation” concept with CDI but with a different reactivity window, enabling comparisons of activation strength and side-reaction windows. | |
Synthetic reagent | Sulfonyl azidation (to sulfonyl azide / azide source) | 952234-36-5 | 1H-Imidazole-1-sulfonyl azide hydrochloride | ≥95% | A typical diazotransfer reagent: used to convert primary amines into the corresponding organic azides; assess and handle under organic azide/hazardous chemical safety norms—avoid treating it as a “mild universal azide source.” |
Table E | Platform Systems | N-Alkylimidazole Precursors + Ionic Liquids (Imidazolium Salts) + NHC Precursors
Category | CAS No. | Aladdin Cat. No. | Name | Specification / Purity | Product features & applications |
N-alkylimidazole | Catalytic base / ligand precursor / curing accelerator | 616-47-7 | 1-Methylimidazole | ≥99% | Common organic base and N-donor ligand: used in nucleophilic catalysis (e.g., acylation/condensation), epoxy curing acceleration, and as a precursor for coordination/ionic-liquid synthesis; a basic small-molecule tool for tuning “basicity/nucleophilicity.” | |
N-alkylimidazole | Organic base / ligand (substitution-effect control) | 1739-84-0 | 1,2-Dimethylimidazole | ≥98% | Substituted imidazole base: used in nucleophilic catalysis and coordination systems; suitable for structural controls linking “increased substitution/sterics → changes in basicity and reactivity,” and also used as a precursor for ionic liquids/salts. | |
N-alkylimidazole | Ionic-liquid precursor / catalysis & coordination | 7098-07-9 | 1-Ethylimidazole | ≥98% (GC) | Representative N-alkylimidazole: used as a precursor to ionic liquids and coordination systems, and also as a base/ligand in organic and materials reactions; often used to probe “ethyl substitution → changes in solubility and reactivity.” | |
N-alkylimidazole | Ionic-liquid precursor / solvent & coordination tool | 4316-42-1 | 1-Butylimidazole | ≥98% (GC) | N-alkylimidazole: commonly used to synthesize imidazolium ionic liquids, and also as an organic base/ligand and a solvation-control tool; suitable for comparing “alkyl chain length → hydrophobicity/viscosity/phase behavior.” | |
Ionic liquid | Imidazolium salt (EMIM⁺/Cl⁻) | 65039-09-0 | 1-Ethyl-3-methylimidazolium chloride | ≥98% | Chloride-form imidazolium ionic liquid: often used as a precursor for ionic-liquid synthesis (anion exchange to BF₄⁻/PF₆⁻/TFSI⁻, etc.); also used to dissolve/stabilize strongly polar or ionic systems (a “solvation platform” role similar to BMIMCl). | |
Ionic liquid | Imidazolium salt (EMIM⁺/BF₄⁻) | 143314-16-3 | 1-Ethyl-3-methylimidazolium tetrafluoroborate (EMIMBF₄) | ≥98% | Representative imidazolium ionic liquid: commonly used in electrochemical electrolytes, catalytic media, and extraction/separation systems; suitable for “anion switching → viscosity/polarity/phase behavior/electrochemical window” comparisons vs TFSI⁻/PF₆⁻/Cl⁻ systems. | |
Ionic liquid | Imidazolium salt (TFSI⁻, electrochemistry / solvent platform) | 174899-82-2 | 1-Ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide | ≥99% | Representative imidazolium ionic liquid: low volatility with a relatively wide electrochemical window; commonly used in electrolytes/electrochemical systems, catalysis, and separation media; also explored as a “solvent platform” to dissolve/stabilize certain poorly soluble systems. | |
Ionic liquid | Imidazolium salt (BMIM⁺/Cl⁻, solvation platform) | 79917-90-1 | 1-Butyl-3-methylimidazolium chloride (BMIMCl) | ≥98% | Representative chloride ionic liquid: commonly used for dissolution/processing studies of cellulose/polysaccharides, ionic-interaction models, and catalytic media; also widely used as a starting material for anion exchange to prepare other BMIM⁺ ionic liquids. | |
Ionic liquid | Imidazolium salt (BMIM⁺/BF₄⁻) | 174501-65-6 | 1-Butyl-3-methylimidazolium tetrafluoroborate (BMIMBF₄) | ≥98% | Representative imidazolium ionic liquid: used in electrochemistry, catalysis, and extraction/separation research; suitable for comparing how anions (BF₄⁻ vs TFSI⁻ vs Cl⁻) affect viscosity, polarity, and phase behavior. | |
Ionic liquid | Imidazolium salt (BMIM⁺/TFSI⁻) | 174899-83-3 | 1-Butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (BMIMTFSI) | ≥98% | Common ionic liquid: relatively wide electrochemical window and good ionic conductivity; widely used as an electrolyte solvent, catalytic medium, and separation medium; suitable for solvent/additive screening in electrochemical/battery systems. | |
Ionic liquid | Imidazolium salt (BMIM⁺/PF₆⁻) | 174501-64-5 | 1-Butyl-3-methylimidazolium hexafluorophosphate | ≥97% | Common PF₆⁻-type ionic liquid: used in electrochemistry, extraction/separation, and catalytic media; comparing with BF₄⁻/TFSI⁻/Cl⁻ helps evaluate differences in hydrophobicity, viscosity, and phase separation behavior. | |
NHC precursor | Bulky aryl imidazolium salt (ligand precursor) | 141556-45-8 | 1,3-Bis(2,4,6-trimethylphenyl)imidazolium chloride | ≥97% | Representative “bulky aryl imidazolium” scaffold: commonly used as an NHC (N-heterocyclic carbene) ligand precursor for metal complexes/catalytic system construction; Mes substitution provides steric and electronic tuning, suitable for comparing catalytic activity and stability. | |
NHC precursor | IPr-type imidazolium salt (ligand precursor) | 258278-25-0 | 1,3-Bis(2,6-diisopropylphenyl)imidazolium chloride | ≥97% | Representative IPr scaffold imidazolium salt: a high-frequency NHC precursor for preparing metal–NHC catalysts (commonly seen in cross-coupling, olefin metathesis/hydrogenation, etc.); used for ligand-series comparisons with stronger steric/electronic effects. |
Note: The above are representative Aladdin products. For additional specifications, please refer to the full product list at the end of the document, or search the Aladdin website using “product name / CAS / catalog number.”
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