Work

Framework Reorganization Governing Optical Transparency and Dielectric Switching in [TMA] 4 [Zn(SCN) 4 ][Zn(SCN) 3 Cl]

Year: 2026

Type: article

Abstract: An organic–inorganic hybrid thiocyanate, [TMA] 4 [Zn(SCN) 4 ][Zn(SCN) 3 Cl], was synthesized, and its structural, vibrational, optical, and dielectric properties were investigated. Single-crystal X-ray diffraction reveals a triclinic centrosymmetric structure (P1̅) comprising two distinct Zn 2+ coordination environments, including tetrahedral ZnN 4 units and ZnN 3 Cl 2 motifs forming infinite Zn–Cl–Zn chains. The framework is stabilized by tetramethylammonium cations through weak C–H···S and C–H···Cl interactions. Spectroscopic studies confirm N-bound thiocyanate coordination. Thermal analysis shows a reversible first-order phase transition near 292 K. Optical measurements indicate a wide direct band gap of 4.55–4.70 eV and strong deep-UV absorption with high transparency in the visible range. Dielectric studies reveal an unusual inverse dielectric switching across the phase transition, with a decrease in permittivity upon heating. These results identify [TMA] 4 [Zn(SCN) 4 ][Zn(SCN) 3 Cl] as a hybrid thiocyanate framework exhibiting thermally tunable dielectric behavior and deep-UV filtering capability.

Source: The Journal of Physical Chemistry C

DOI: 10.1021/acs.jpcc.5c08582