Thermochromism of rapid responses to temperature changes versus mechanochromism in a Ni-dithiolene complex salt

Abstract

A thermochromic or mechanochromic material can switch between at least two stable states in response to changes in temperature or static pressure/strain. In this study, we investigated a Ni-dithiolene dianion...

Polymorph transformation in a mixed-stacking nickel-dithiolene complex with the derivative of 4,4′-bipyridinium

“…Initially formed as a red-colored precipitate in an aqueous solution, it later transformed into a green sample upon exposure to ultrasound in MeOH. 32 Comparative microanalysis of both 1 -g and 1 -r (ESI†) revealed relative C, H, and N element contents consistent with the calculated values for the formula C 26 H 26 N 6 NiS 4 , indicating identical chemical composition in both 1 -g and 1 -r, and both are two polymorphic forms of [C 4 -4,4′-BiPy][Ni(mnt) 2 ].…”

“…Bond lengths and angles within both the cation and the anion adhere to standard ranges. 32,38,39 The anions (A) and the cations (C) are arranged in a mixed-stacking fashion of …CACA… along the a -axis direction (Fig. 4b), with identical distances of Ni in the anion to the midpoint of the C7–C7#1 bond in the cation within a mixed-stacking column.…”

“…Such a type of alignment is distinct from that observed in other [1,1′-di- R -4,4′-BiPy][M(mnt) 2 ] (herein, M = Ni, Cu, Pd or Pt; 1,1′-di- R -4,4′-BiPy 2+ is the cation of 1,1′-dialkyl-4,4′-bipyridinium, 1,1′-diphenyl-4,4′-bipyridinium or 1,1′-dibenzyl-4,4′-bipyridinium). 32,38–42 The mean-molecule planes of [Ni(mnt) 2 ] 2− , defined by the NiS 4 core in the anion, and the two coplanar pyridyl rings in the cation, display nearly parallel stacking with a 3.03(1)° dihedral angle within a mixed-stacking column. The mean-molecule planes of [Ni(mnt) 2 ] 2− make a dihedral angle of 57.83(2)° between the neighboring mixed-stacking columns along the c -axis direction (Fig.…”

“…Notably, this represents the initial instance of polymorphism observed in the [Ni(mnt) 2 ] 2− salt, marking a unique discovery. 32 To broaden the scope of this investigation, considering the potential impact of alkyl chain lengths within 1,1′-dialkyl-4,4′-bipyridinium cations on the crystal packing, we examined the crystal structure and dielectric properties of [C 4 -4,4′-BiPy][Ni(mnt) 2 ] ( 1 ; C 4 -4,4′-BiPy 2+ represents 1,1′-dibutyl-4,4′-bipyridinium). Our findings revealed that 1 exhibits two different crystalline forms, each undergoing a reversible phase transition.…”

Thermotropic Structure Phase Transitions and Two Types of Thermochromic Behaviors in a Bromoargentate Cluster [Pr-dabco]2Ag4Br6

“…During the cooling process, the trend of the dielectric permittivity changing with temperature is similar to that during the heating process. Clearly, the dielectric anomaly observed in 1 is relevant to the structure phase transition. − …”