Per-6-O-(tert-butyldimethylsilyl)cyclodextrins (TBDMS-CDs) in Langmuir Monolayers:  The Importance of a Spreading Solvent in the Preparation of LB Layers Suitable for Sensor Application

• Published in: The journal of physical chemistry. B Vol. 112; no. 15; pp. 4620 - 4628
• Main Authors: Flasiński, Michał, Broniatowski, Marcin, Romeu, Nuria Vila, Dynarowicz-Ła̧tka, Patrycja, Moreno, Amparo Gallardo, Vilas, Antonio Mendez, González Martín, M. Luisa
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 17.04.2008
• Subjects: 2-Propanol - chemistry; Aluminum Silicates - chemistry; Cadmium - chemistry; Chloroform - chemistry; Cyclodextrins - chemistry; Electrodes; Hexanes - chemistry; Membranes, Artificial; Molecular Structure; Particle Size; Reproducibility of Results; Solvents - chemistry; Stearates - chemistry; Stereoisomerism; Surface Properties
• ISSN: 1520-6106; 1520-5207
• DOI: 10.1021/jp711083n

Commercially available amphiphilic cyclodextrins, namely per-6-O-(tert-butyldimethylsilyl) α, β and γ cyclodextrins (TBDMS−α-, −β-, and −γ-CDs) were subjected to a thorough Langmuir monolayer characterization, using both traditional methods of surface manometry (π/A isotherms, stability experiments) and modern micrometer/nanometer resolution (BAM, AFM) surface techniques. It has been found that inconsistent behavior regarding the isotherms reproducibility obtained upon compression of TBDMS−β-CDs is due to the aggregation of the investigated molecules in chloroform and hexane, while good reproducibility ensured a mixed spreading solvent system of hexane/isopropanol 7:3 (v/v). Although the stability of films dropped from chloroform and hexane/isopropanol solvents below the equilibrium surface pressure (ESP) was comparable, pronounced differences were observed at pressures above ESP. The investigated TBDMS−CDs were successfully transferred onto cadmium stearate covered mica substrates. AFM images confirmed the presence of discontinuous multilayered films (10 nm heights) spread from chloroform versus monomolecular dispersion achieved in hexane/isopropanol.