Control of Self-Organization of Thiacalix[4]Crown-Ethers in Cone and 1,3-Alternate Forms in Nanofilms on Quartz Substrate
摘要
Morphological characteristics of the nanolayers of amphiphilic tert-butylthiacalix[4]crown-4-ether in cone stereoisomeric form 1 and bolaamphiphilic nitrothiacalix[4]biscrown-5-ether in 1,3-alternate form 2 deposited onto quartz substrate at varying solvent, temperature, and concentration of compounds are analyzed. Quantum-chemical calculations of the considered calix[4]arenes reveal a favorable micellar aggregation (the packing factor p < 0.3). During AFM visualization of calixarene nanolayers prepared through evaporation of solvent on substrate, spherical associates that are 200–800 nm in size are detected for compound 1, which enlarge with a decrease in the concentration of compound and an increase in solvent polarity and environmental temperature. At the same time, the dispersity of the sizes of associates increases with a decrease in temperature, but has a mixed dependence on solvent and concentration. The most uniform size distribution of spherical particles is achieved upon Langmuir monolayer formation at the air–water interface upon deposition of the solution of compound 1 in 10–5 M solution in chloroform onto water subphase and upon vertical transfer onto substrate. In the case of bolaamphiphile 2, spherical associates are formed at t = 23°C in 10–5 М solution in toluene and at 4°С in 10–4 М solution in chloroform, while under other combinations of conditions, the nanofilm is represented by thread-like structures (at 23°С) and tactoid aggregates (at 4°С). Dynamic light scattering study of the solutions of amphiphile 1 in chloroform allows to detect spherical aggregates (particle size is 202 ± 92 nm), which indicates the decisive role of solvent in the formation of spherical aggregates in nanolayers, while in other cases the supramolecular organization of calixarenes is presumably affected by the interaction with substrate.