Solvent effects on nucleation of disodium guanosine 5′-monophosphate in anti-solvent/water mixtures. Issue 35 (1st August 2016)

• Record Type: Journal Article
• Authors: Zou, Fengxia; Zhuang, Wei; Chen, Qiao; Yang, PengPeng; Lin, Chenguang; Jiao, Pengfei; Zhou, Jingwei; Wu, Jinglan; Ying, Hanjie
• Is Part Of: CrystEngComm. Volume 18:Issue 35(2016)
• Page Start: 6653
• Page End: 6663
• Publication Date: 2016-08-01
• Subjects: Crystals -- Periodicals; Crystal growth -- Periodicals; Crystallography -- Periodicals; Cristaux -- Périodiques; Cristaux -- Croissance -- Périodiques; Cristallographie -- Périodiques; 548
• DOI: 10.1039/c6ce00867d
• Languages: English
• ISSNs: 1466-8033

Abstract

Abstract : A surface entropy factor ( f b ) was introduced to explain that crystals were formed when f b > 5 in binary solutions regardless of supersaturation. Abstract : The influence of the solvent on the nucleation of disodium guanosine 5′-monophosphate (GMPNa2 ) in eight methanol (ethanol)–water mixtures and at three supersaturation levels at 293.15 K was investigated. The interfacial free energy, the critical size for nucleation, and the number of molecules were calculated using equations re-derived from the classical nucleation theory. GMPNa2 nucleation involves not only a primary nucleation process but also the conversion from a homogeneous to a heterogeneous process. The transformation experiment indicated that the nucleation of GMPNa2 follows the two-step model. A surface entropy factor ( f b ) was proposed to relate the solvent composition and interfacial free energy in order to explain the solvent effects on the nucleation process. Although the f b values can be used to judge the crystal growth mode, nucleation and growth cannot be separated, since pure primary nucleation does not occur for this compound. The f b values clearly increased with increasing solvent content and decreasing supersaturation. For the homogeneous process in a methanol–water system, regular crystals can be formed only when f b > 5, regardless of the supersaturation, as was observed for solvent contents of 40 mol% and 30 mol% ( S = 1.83 and 1.70, respectively). These results can help select a suitable solvent system and its composition during anti-solvent crystallization.