Journal of Crystal Growth, Vol.448, 6-16, 2016
Germ direct observation by AFM under crystallization of self-organized assemblies of mono-protonated meso-tetraphenylporphine dimers
Assemblies consisting of mono-protonated meso-tetraphenylporphine dimers and water have been investigated by UV-vis spectroscopy in solution and atomic force microscopy (AFM) in thin layers. These assemblies self-organized into domains produce microcrystals in thin layer. Morphology of the microcrystals and characteristic features of crystallization germ on the top found by contact AFM indicate that surface tension of an aqueous layer on the domain generates the crystallization process. Estimations of the pressure producing the germ and bulk modulus (13,,) of microcrystals give 26.3 +/- 2.6 MPa and 3.72 GPa and B-m = 12.7 GPa obtained for dried thin films. The former modulus is comparable with bulk modulus of water (2.174 GPa) that implies liquid crystals formation. Absorptions of longitudinal optical (LO) phonons with (h) over bar omega LO = 0.3761 and 0.3577 eV, which are arisen because of hole polaron moving through water, are found in the electronic spectra of the assemblies. The crystallization is suggested to occur due to Zundel cation (H5O2+) operation like the water-porphyrin matrix self-organization found earlier. (C) 2016 Elsevier B.V. All rights reserved.