Crystals of Linear Oligophenyls: Surface Properties, Nucleation and Growth

Abstract

Crystals of linear oligophenyls p-nP (n is the number of phenyl groups) are of interest for organic electronics and photonics as effective blue emitters and scintillators. The surface properties and external conditions of the growth medium are the determining factors in the nucleation and formation of crystals. However, the crystallization processes of conjugated linear molecules are still understudied and there is practically no experimental data on the surface properties of solutions and crystals. At the same time, there are few studies in the literature on modeling the surface energy of the crystal faces of these substances [1]. This work presents the results of studying of the linear oligophenyls (n = 2..6) crystals growth from solutions and the vapor phase. In the approximation of the OPLS atomic force field method, the values of the surface energy of the (100), ( 010), (110), and (001) faces of the crystals are determined. Based on the data on the crystal structure and the obtained values of the surface energy of the faces, the morphology of the crystals is analyzed and their equilibrium shapes are predicted. Within the framework of the classical nucleation theory, the parameters of crystal nucleation under experimental conditions of growth from solutions and physical vapor transport are studied.

Crystals of Diphenyl-Benzothiadiazole and Its Derivative with Terminal Trimethylsilyl Substituents: Growth from Solutions, Structure, and Fluorescence Properties

“…The surface morphology and thickness of the crystals were studied using a LEXT OLS 3100 confocal microscope (Olympus, Japan) and an Ntegra atomic force microscope (NT-MDT, Russia) in contact mode according to the method described earlier. 21 The AFM topograms obtained were processed and analyzed using the Gwyddion program. 22…”

“…The concentration of saturated solutions of the compounds in n-hexane was measured spectrophotometrically. 21 The solutions were kept for 24 h over the crystalline precipitate formed at a temperature of 303 K, filtered through poly(tetrafluoroethylene) (PTFE) filters (0.22 μm), and diluted a known number of times so that the optical density did not exceed 0.6 at long-wavelength maxima. The absorption spectra of solutions were measured on a UV-2501PC spectrophotometer (Shimadzu, Japan) in standard quartz cuvettes with a 10 mm optical path.…”