Prof. Ashwini Nangia's Research Group

Recent Publication:

The design and synthesis of mechanically responsive materials is interesting because they are potential candidates to convert thermal energy into mechanical work. Reported in this paper are thermosalient effects in a series of halogen derivatives of salinazids. The chloro derivative, with higher electronegativity and a weaker inter-halogen bond strength (Cl…Cl) exhibits an excellent thermal response, whereas the response is weaker in the iodo derivative with stronger I…I halogen bonding. 3,5-Dichlorosalinazid (Compound-A) exists in three polymorphic forms, two room-temperature polymorphs (Forms I and II) and one high-temperature modification (Form III). The transformation of Form I to Form III upon heating at 328–333 K is a reversible thermosalient transition, whereas the transformation of Form II to Form III is irreversible and nonthermosalient. 3,5-Dibromo- (Compound-B) and 3-bromo-5-chloro-(Compound-C) salinazid are both dimorphic: the Form I to Form II transition in Compound-B is irreversible, whereas Compound-C shows a reversible thermosalient effect (362–365 K). In the case of 3,5-diiodosalinazid (Compound-D) and 3,5-difluorosalinazid (Compound-E), no phase transitions or thermal effects were observed. The thermosalient behaviour of these halosalinazid molecular crystals is understood from the anisotropy in the cell parameters (an increase in the a axis and a decrease in the b and c axes upon heating) and the sudden release of accumulated strain during the phase transition. The dihalogen salinazid derivatives (chlorine to iodine) show a decrease in thermal effects with an increase in halogen-bond strength. Interestingly, Compound-B shows solid-state photochromism in its polymorphs along with the thermosalient effect, wherein Form I is cyan and Form II is light orange.

Authors: Sudhir Mittapalli,a D. Sravana kumar Perumalla,b Jagadeesh Babu Nanuboluc and Ashwini Nangiaa,d*

aSchool of Chemistry, University of Hyderabad, Professor C. R. Rao Road, Gachibowli, Hyderabad 500 046,  India,

bDepartment of Inorganic and Physical Chemistry, Indian Institute of Science, Bengaluru 500 016, India, cCSIR- Indian Institute of Chemical Technology, Tarnaka, Hyderabad 500 007, India,

dCSIR-National Chemical Laboratory, Dr Homi Bhabha Road, Pune 411 008, India. *Correspondence e-mail: ashwini.nangia@gmail.com

 

                                            Publication date : October 10th, 2017



Recent Announcements

  • Section editor of Acta Crystallographica Section B Wrriten by Prof. Desiraju: It's a pleasure to record the appointment of Prof. Ashwini Kumar Nangia, Director, National Chemical Laboratory, Pune as a main editor of Acta Crystallographica Section ...
    Posted May 19, 2017, 3:18 AM by Ashwini Nangia
  • Twenty-Fourth Congress and General Assembly of the International Union of Crystallography India will host the 24th Congress & General Assembly of the International Union of Crystallography 2017 from 21 – 28 August 2017. We extend a warm welcome to all crystallographers from across ...
    Posted Sep 8, 2016, 5:11 PM by Ashwini Nangia
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