Two-component self-assembly with solvent leading to "wet" and microcrystalline organogel fibers

Miika Löfman; Manu Lahtinen; Kari Rissanen; Elina Sievänen

doi:10.1016/j.jcis.2014.09.062

Two-component self-assembly with solvent leading to "wet" and microcrystalline organogel fibers

J Colloid Interface Sci. 2015 Jan 15:438:77-86. doi: 10.1016/j.jcis.2014.09.062. Epub 2014 Oct 2.

Authors

Miika Löfman¹, Manu Lahtinen², Kari Rissanen², Elina Sievänen³

Affiliations

¹ Department of Chemistry, P.O. Box 35, FI-40014 University of Jyväskylä, Finland. Electronic address: miika.lofman@mykolab.ch.
² Department of Chemistry, P.O. Box 35, FI-40014 University of Jyväskylä, Finland.
³ Department of Chemistry, P.O. Box 35, FI-40014 University of Jyväskylä, Finland. Electronic address: elina.i.sievanen@jyu.fi.

PMID: 25454428
DOI: 10.1016/j.jcis.2014.09.062

Abstract

Hypothesis: The microcrystalline fibers of N-(2-aminoethyl)-3α-hydroxy-5β-cholan-24-amide 1 provided a useful model system for studying the complex relationship between morphology, experimental parameters, solvent, and the phenomenon of organogelation. The presence of solvents in the solid forms of 1 along with crystallization behavior suggested solvate formation and polymorphic behavior.

Experiments: Forty solid state- and xerogel samples of 1 formed in organic solvents and in three categories of experimental conditions were analyzed with single crystal X-ray diffraction (XRD), powder X-ray diffraction (PXRD), Raman microscopy, and attenuated total reflection Fourier-transform infrared spectroscopy (ATR FTIR).

Findings: Two polymorphs and four isostructural aromatic solvates of 1 were found among some unknown forms in the samples. Single crystal X-ray structures of one polymorph and bromobenzene solvate were obtained, the latter from a xerogel. Multiple crystal forms could be present in a sample, and their contributions to gelation were estimated taking the experimental conditions into account. Gelator 1 could act as a variable component gelator, either alone or in combination with an aromatic solvent. The research brings new insight into the structures of microcrystalline organogel fibers, linking solvate/inclusion crystal formation with microcrystalline fibers of an organogelator for the first time.

Keywords: Bile acid amide; Crystallization; Fourier transform infrared spectroscopy; Inclusion crystal; Microcrystalline fiber; Organogel; Raman microscopy; Solvate; X-ray crystallography; Xerogel.