Polymorphism and Phase Transformation Behavior of Solid Forms of 4-Amino-3,5-dinitrobenzamide

Reddy, Prakasha J and Swain, Diptikanta and Pedireddi, VR (2014) Polymorphism and Phase Transformation Behavior of Solid Forms of 4-Amino-3,5-dinitrobenzamide. In: CRYSTAL GROWTH & DESIGN, 14 (10). pp. 5064-5071.

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Abstract

We report the preparation, analysis, and phase transformation behavior of polymorphs and the hydrate of 4-amino-3,5-dinitrobenzamide. The compound crystallizes in four different polymorphic forms, Form I (monoclinic, P2(1)/n), Form II (orthorhombic, Pbca), Form III (monoclinic, P2(1)/c), and Form IV (monoclinic, P2(1)/c). Interestingly, a hydrate (triclinic, P (1) over bar) of the compound is also discovered during the systematic identification of the polymorphs. Analysis of the polymorphs has been investigated using hot stage microscopy, differential scanning calorimetry, in situ variable-temperature powder X-ray diffraction, and single-crystal X-ray diffraction. On heating, all of the solid forms convert into Form I irreversibly, and on further heating, melting is observed. In situ single-crystal X-ray diffraction studies revealed that Form II transforms to Form I above 175 degrees C via single-crystal-to-single-crystal transformation. The hydrate, on heating, undergoes a double phase transition, first to Form III upon losing water in a single-crystal-to-single-crystal fashion and then to a more stable polymorph Form I on further heating. Thermal analysis leads to the conclusion that Form II appears to be the most stable phase at ambient conditions, whereas Form I is more stable at higher temperature.

Item Type:	Journal Article
Publication:	CRYSTAL GROWTH & DESIGN
Publisher:	AMER CHEMICAL SOC
Additional Information:	Copy right for this article belongs to the AMER CHEMICAL SOC, 1155 16TH ST, NW, WASHINGTON, DC 20036 USA
Department/Centre:	Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Date Deposited:	14 Nov 2014 07:26
Last Modified:	14 Nov 2014 07:26
URI:	http://eprints.iisc.ac.in/id/eprint/50258

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