How do cucurbiturils differ from cyclodextrins?

Both are aqueous hosts, but cucurbiturils have a far more rigid, shape-persistent cavity fringed at both rims by electron-rich carbonyl portals that provide ion–dipole, hydrogen-bonding and hydrophobic contacts simultaneously. In well-matched systems CB[7] association constants can exceed common cyclodextrins by several orders of magnitude, and the CB[5]–CB[10] series offers a more continuous size ladder.

How should I choose the right CB[n] homologue for my guest?

Start with size: the largest guest cross-section must be smaller than the portal diameter (CB[5] 2.4 Å, CB[6] 3.9 Å, CB[7] 5.4 Å, CB[8] 6.9 Å, CB[10] 8.9 Å). Then consider the medium — for concentrated aqueous work prefer the modified, highly water-soluble series. Finally consider the goal: CB[8] for ternary crosslinks, unsubstituted CB[n] for direct comparability with classical literature data.

Why use highly water-soluble modified cucurbiturils?

Unsubstituted CB[5] and CB[6] pack through dense intermolecular hydrogen bonds and dissolve poorly, making millimolar aqueous stocks difficult. Methylation and cyclohexano/cyclobutano fusion weaken that packing and markedly improve solubility while retaining the rigid cavity and carbonyl portals — better suited to biological, sensing and aqueous materials work.

How is CB[7] typically used in drug delivery research?

Typically CB[7] encapsulates a hydrophobic or cationic motif of the drug, increasing apparent solubility, suppressing hydrolysis and photodegradation, and masking bitterness or mucosal irritation. Release can be triggered by a competitive guest (e.g. an adamantylamine derivative), a pH change or a redox stimulus. Formulations must be validated case by case against drug structure, buffer and concentration.

How is product purity and analytical data confirmed?

All regular and modified cucurbituril products on this site carry a uniform ≥98% purity grade, assigned primarily by HPLC assay and supported by ¹H/¹³C NMR confirmation, mass spectrometry, elemental analysis and Karl Fischer water determination. Batch-specific reports and spectral data are available on request before ordering.

Do you support custom synthesis and small trial quantities?

Yes. Standard homologues are stocked from milligram to gram scale for condition screening; special substitution patterns, specific homologues or larger quantities can be arranged through custom synthesis, following request submission, technical assessment, quotation, synthesis and QC-based delivery.

Product Catalog

Cucurbituril-X delivers high-purity cucurbit[n]uril materials, including cucurbit[5]uril (CB[5]), cucurbit[6]uril (CB[6]), cucurbit[7]uril (CB[7]), cucurbit[8]uril (CB[8]), and functionalized cucurbituril derivatives for supramolecular chemistry research.

We also offer highly water-soluble modified cucurbituril products, including methylated, cyclohexyl and cyclobutyl derivative series, for biological applications and advanced supramolecular chemistry research.

Our products are ideal for host–guest chemistry, molecular recognition, drug delivery research, catalysis, sensing, and advanced functional materials.

Cucurbit[5]uril

CAS:259886-49-2

Formula: C₃₀H₃₀N₂₀O₁₀·10H₂O

Purity: ≥98%

Specifications: 500mg / 1g / 5g / 10g

$280

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Cucurbit[6]uril

CAS:80262-44-8

Formula: C₃₆H₃₆N₂₄O₁₂·10H₂O

Purity: ≥98%

Specifications: 1g / 5g / 10g / 100g

$22

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Cucurbit[7]uril

CAS:259886-50-5

Formula: C₄₂H₄₂N₂₈O₁₄·10H₂O

Purity: ≥98%

Specifications: 500mg / 1g / 5g / 10g

$280

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Cucurbit[8]uril

CAS:259886-51-6

Formula: C₄₈H₄₈N₃₂O₁₆·10H₂O

Purity: ≥98%

Specifications: 500mg / 1g / 5g / 10g

$280

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Cucurbit[10]uril

CAS:307001-50-9

Formula: C₆₄H₇₆N₄₀O₂₀·10H₂O

Purity: ≥98%

Specifications: 50 0mg / 1g / 2g / 5g

$1,120

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Symmetrical tetramethyl cucurbit[6]uril

CAS:Available upon request

Formula: C₄₀H₄₄N₂₄O₁₂·10H₂O

Purity: ≥98%

Specifications: 500mg / 1g / 5g / 10g

$392

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Permethylated cucurbit[5]uril

CAS:Available upon request

Formula: C₄₀H₅₀N₂₀O₁₀·10H₂O

Purity: ≥98%

Specifications: 50mg / 100mg / 200mg / 500mg

$420

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Permethylated cucurbit[6]uril

CAS:Available upon request

Formula: C₄₈H₆₀N₂₄O₁₂·10H₂O

Purity: ≥98%

Specifications: 50mg / 100mg / 200mg / 500mg

$420

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Cyclohexyl cucurbit[5]uril

CAS:Available upon request

Formula: C₅₀H₆₀N₂₀O₁₀·10H₂O

Purity: ≥98%

Specifications: 50mg / 100mg / 200mg / 500mg

$490

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Cyclohexyl cucurbit[6]uril

CAS:Available upon request

Formula: C₆₀H₇₂N₂₄O₁₂·10H₂O

Purity: ≥98%

Specifications: 50mg / 100mg / 200mg / 500mg

$490

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1,3,5-Tricyclohexyl Cucurbit[6]uril

CAS:Available upon request

Formula: C₄₈H₅₄N₂₄O₁₂·10H₂O

Purity: ≥98%

Specifications: 50mg / 100mg / 200mg / 500mg

$490

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Cyclobutanocucurbit[5]uril

CAS:Available upon request

Formula: C₄₀H₄₈N₂₀O₁₀·10H₂O

Purity: ≥98%

Specifications: 50mg / 100mg / 200mg / 500mg

$840

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Cyclobutanocucurbit[6]uril

CAS:Available upon request

Formula: C₄₈H₄₈N₂₄O₁₂·10H₂O

Purity: ≥98%

Specifications: 50mg / 100mg / 200mg / 500mg

$840

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Structural and Physical Parameters of Cucurbit[n]urils

Cucurbit[n]urils are rigid, barrel-shaped macrocycles composed of n glycoluril units linked by methylene bridges, with the general formula (C6H6N4O2)n.. As n increases, both the cavity volume and portal diameter expand, directly governing the size and selectivity of guest molecules that can be accommodated. The geometric parameters below represent values most commonly cited in the literature and serve as an initial screening basis for host selection.

Structural and physical parameters of cucurbit[n]uril homologues
Homolog	Formula	MW	CAS	Cavity (Å³)	Portal (Å)	Outer Diameter (Å)	Height (Å)
CB[5]	C30H30N20O10	822.65	259886-49-2	82	2.4	13.1	8.2
CB[6]	C36H36N24O12	996.82	80262-44-8	164	3.9	13.4	9.1
CB[7]	C42H42N28O14	1162.99	259886-50-5	279	5.4	16.0	11.4
CB[8]	C48H48N32O16	1329.15	259886-51-6	479	6.9	17.5	12.4
CB[10]	C60H60N40O20	1657.49	307001-50-9	870	8.9	20.0	13.7

Note: Cavity volume, portal diameter, outer diameter, and height are theoretical values based on crystal structures commonly cited in the literature. Actual usable space depends on guest molecule shape, solvation, and portal water molecules. CAS numbers correspond to our product pages; click a homologue code to view the related product.

Solubility, Typical Guests, and Application Areas

Unsubstituted cucurbiturils pack via dense intermolecular hydrogen bonds, leading to marked solubility differences across the series: CB[5] and CB[6] are poorly water-soluble, CB[7] is readily soluble, while CB[8] and CB[10] fall in between. Solubility determines the working medium and stock solution preparation, making it as critical as cavity size when selecting a host.

Solubility, Typical Guest Molecules, and Applications of Cucurbit[n]uril Homologues
Homolog	Solubility	Typical guests	Typical applications
CB[5] Cucurbit[5]uril	Low water solubility	Small gas molecules (CO₂, CH₄), small amines, and metal-ion complexes	Molecular recognition, gas adsorption and storage, ion channel models, confined catalysis
CB[6] Cucurbit[6]uril	Low water solubility; soluble in formic acid or acidic media	Short-chain alkyl diammonium salts, protonated aliphatic amines, small cations	Supramolecular assembly, molecular containers, crystal engineering, confined reactions
CB[7] Cucurbit[7]uril	Good; aqueous solutions at tens of mmol/L	Ferrocene, adamantylamine, aromatic ammonium salts, and various drug molecules	Drug delivery and solubilization, fluorescence/electrochemical sensing, molecular switches, and biological recognition
CB[8] Cucurbit[8]uril	Moderate water solubility	Ternary host–guest–guest complexes (methyl viologen + naphthol / amino acid / peptide)	Self-healing hydrogels, supramolecular polymers, photochemical control, peptide recognition
CB[10] Cucurbit[10]uril	Moderate; typically isolated as a CB[10]·CB[5] inclusion complex	Proteins, macromolecular guests, nanoparticle surface ligands, dendrimers	Macromolecule encapsulation, nanomaterial assembly, protein surface recognition, and large-cavity container chemistry

Cucurbituril Selection Guide

Four dimensions — guest size, solvent system, application area, and required scale — help you quickly narrow down the right homologue and pack size.

Match guest count to cavity size

The guest's largest cross-section must be smaller than the portal diameter. CB[5] (≈2.4 Å) accepts only very small guests, CB[7] (≈5.4 Å) accommodates aromatic rings and adamantyl groups, and CB[8] (≈6.9 Å) can host two guests as a ternary complex.

Select the series by solvent system

For concentrated host solutions in pure water or buffer, prefer the methylated, cyclohexyl, or cyclobutyl-modified series. When working with formic acid, DMSO, or acidic media, unsubstituted CB[6] is also suitable.

Select the homologous product by application

Drug delivery and sensing typically use CB[7]; self-healing hydrogels and ternary complexation use CB[8]; gas adsorption and small-molecule recognition use CB[5]/CB[6]; protein and macromolecule encapsulation uses CB[10].

Select pack size by scale

Milligram quantities are ideal for condition screening and binding-constant measurements; gram quantities suit material preparation and scale-up. Standard homologues are in stock, while custom synthesis is available for special substitution patterns or larger quantities.

Design Rationale for Water-Soluble Modified Cucurbiturils

When a study requires concentrated host solutions in water or buffer, the solubility of unsubstituted CB[5] and CB[6] often becomes a bottleneck. The modified series enhances solubility by weakening intermolecular hydrogen-bond packing while preserving the rigid cavity and recognition behavior at both carbonyl portals.

The problem: solubility

Unsubstituted CB[5] and CB[6] form dense intermolecular hydrogen-bond networks, dissolve poorly in water and most organic solvents, making concentrated aqueous host solutions difficult to prepare and limiting their biological and solution-phase applications.

Strategy 1: methylation

Introducing methyl groups onto the glycoluril skeleton (TMeCB[6], Me10CB[5], Me12CB[6]) disrupts intermolecular hydrogen-bond packing, significantly enhances water solubility, and largely preserves the rigid cavity and carbonyl-portal recognition behavior.

Strategy 2: cyclohexane fusion

Cyclohexano-fused series (Cy5CB[5], Cy6CB[6], 1,3,5-Cy3CB[6]) improve solubility and processability through outwardly projecting cyclohexane rings; cavity dimensions stay close to the parent homologues, so established host–guest design rules still apply.

Strategy 3: cyclobutano fusion

The cyclobutano-fused series (CyB5CB[5], CyB6CB[6]) offers excellent water and alcohol solubility, making it ideal for water/alcohol mixed solvents, coating formulations, and workflows requiring an organic co-solvent.

Cucurbituril Selection and Technical FAQ

Answers to the most common user questions about selection, solubility, purity confirmation, and custom synthesis. For anything not covered here, contact our technical team directly.

Frequently asked questions

Both are aqueous hosts, but cucurbiturils feature a rigid, shape-persistent cavity with electron-rich carbonyl portals at both rims that enable simultaneous ion–dipole, hydrogen-bonding, and hydrophobic interactions. In well-matched systems, CB[7] association constants can exceed those of common cyclodextrins by several orders of magnitude, and the CB[5]–CB[10] series provides a more continuous size range.