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Updated: Aug 5, 2026
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Isolating Free Carbenes, their Mixed Dimers and Organic Radicals
Published on: April 19, 2019
Carba-closo-dodecaborates as Superchaotropic Anions
Andrea Barba-Bon1, Guillermo E Quintero1,2, Maryam Ashjari1
1School of Science, Constructor University, Bremen, Germany.
Chemistry (Weinheim an Der Bergstrasse, Germany)
|July 28, 2026
Summary
The 1-carba-closo-dodecaborate anion (CB11H12-) exhibits strong binding to cyclodextrins (CDs) due to its superchaotropic properties. This smallest known superchaotropic ion effectively transports hydrophilic peptides across lipid membranes.
Area of Science:
- Supramolecular Chemistry
- Boron Cluster Chemistry
- Host-Guest Chemistry
Background:
- Cyclodextrins (CDs) are widely used host molecules with hydrophobic cavities.
- Polyhedral boron cluster anions, including carboranates, have shown potential in catalysis and as ionic liquids.
- Superchaotropic anions are characterized by their ability to disrupt water structure and are known for their charge-dispersed nature.
Purpose of the Study:
- To investigate the host-guest chemistry between 1-carba-closo-dodecaborate anions (CB11H12-) and cyclodextrins (CDs).
- To evaluate the chaotropic properties and membrane transport capabilities of CB11H12- and related boron cluster anions.
- To establish CB11H12- as the smallest superchaotropic ion and correlate its properties with binding and transport activities.
Main Methods:
- Host-guest binding studies using cyclodextrins (α-CD, β-CD) and 1-carba-closo-dodecaborate anions.
- Thermodynamic analysis of anion encapsulation by CDs, including enthalpy and binding constants (Ka).
- Assessment of chaotropic effect using cloud point measurements of hydroxypropylcellulose and transmembrane transport assays with lipid bilayers and cells.
Main Results:
- 1-Carba-closo-dodecaborate anions bind tightly (Ka ≈ 105 M-1) to cyclodextrin cavities, driven by enthalpic contributions (ΔH down to -19 kcal mol-1).
- CB11H12- demonstrates significantly higher binding affinity to CDs compared to the isosteric B12H122-, indicating greater chaotropicity.
- CB11H12- acts as an effective chaotropic transmembrane carrier for hydrophilic peptides (Arg8, phalloidin) across artificial and cellular membranes.
Conclusions:
- 1-Carba-closo-dodecaborate anion is identified as the smallest superchaotropic ion known to date.
- The chaotropic properties of boron cluster anions, including CB11H12-, are key to their strong host-guest interactions with cyclodextrins.
- Superchaotropic boron cluster anions show promise as transmembrane carriers for drug delivery applications, with activity correlating to their volume and charge density.
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