Structural Snapshots of Metastable Intermediates Reveals Sequential Addition of Growth Units in the Formation of an Archetypal Coordination Complex: Anisotropic Layer Migration and Solid-State Thermochromic Transitions

SeethaLekshmi, Sunil and Mangalampalli, Kiran Sri Rama Narasimha and Hareesh, Unnikrishnan Nair S and Ramamurty, Upradrasta and Varughese, Sunil (2016) Structural Snapshots of Metastable Intermediates Reveals Sequential Addition of Growth Units in the Formation of an Archetypal Coordination Complex: Anisotropic Layer Migration and Solid-State Thermochromic Transitions. In: CRYSTAL GROWTH & DESIGN, 16 (12). pp. 7271-7277.

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Abstract

Kinetically trapped partially preassembled metastable structures afford vital inputs on the reaction progression and the formation mechanism of technologically promising coordination assemblies. We report the structural and transformational relations in a series of coordination complexes, Co(ad)(2)(H2O)(4)](btc-)(2)(H2O)(2) (1), Co(ad)(2)(H2O)(4)] Co (H2O)(6)] (btc-)(2)(H2O)(10) (2), Co-3(ad)(2)(H2O)(14)] (btc-)(2)(H2O)(4) (3), and Co-3(ad)(2)(btc)(2)(H2O)(8)] (4), in which ad = adenine and btc = 1,3,5-benzenetricarboxylic acid, to provide insights on sequential structure evolution in an archetypal coordination assembly. Crystals of 3 undergo solid-state thermochromic transformation to a glassy phase 5 consequent to dehydration and anation reaction. With carefully optimized thermal treatment, we obtained a trasient crystalline phase 4, which -> 4 transformation, the crystal surface undergoes drastic modification. Surface reconstruction events associated with photoreactions in the molecular crystals are noted, but analogous observations for thermally induced events are exceptional and unprecedented for coordination complexes. Correlative atomic force microscopy, nanoindentation, and structural inputs provide insights on the surface reconstruction events brought about by anisotropic long-range layer migration subsequent to 3 4 transition. The slip plane (011) that crosses the crystal face (010) at an optimal angle offers an energetically viable route for layer reorientation and migration.

Item Type:	Journal Article
Publication:	CRYSTAL GROWTH & DESIGN
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 Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited:	20 Jan 2017 04:13
Last Modified:	20 Jan 2017 04:13
URI:	http://eprints.iisc.ac.in/id/eprint/55913

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