Structural geometry of the layered perovskite-type (CH3CH2CH2NH3)2CuCl4 single crystal near phase transition temperatures

Seong Eun Jang,Mi Jung Kim,Ae Ran Lim

doi:10.1063/1.5051115

Abstract

Chemical shifts and spin–lattice relaxation times are measured using 1H MAS NMR, 13C CP/MAS NMR, and 14N MAS NMR techniques to understand the structural geometry and dynamics of the alkyl and ammonium groups in layered perovskite (CH3CH2CH2NH3)2CuCl4. Each proton and carbon may be distinguished using MAS NMR. The 1H MAS NMR chemical shifts as a function of temperature showed a larger variation in the ammonium group than in the alkyl group, while the 1H relaxation time (T1ρ) for the ammonium groups was shorter than that of the alkyl group. The paramagnetic Cu2+ ions in the CH3CH2CH2NH3 cation were bonded with the inorganic layer through the N–H···Cl hydrogen bonds, and were paramagnetic, directly affecting the environment of 1H in NH3. The 13C T1ρ values for CH3 increased with temperature, a trend that has been observed in the alkyl group attached to the CH3CH2CH2NH3 cation because of an increased mobility toward its free end.

Highlights

Hybrid organic-inorganic compounds provide a variety of opportunities for scientific study and technological application.[1,2,3,4,5,6,7] This broad range of materials allows the combination of organic and inorganic moieties with different properties within a single structure
FIG. 3. 1H chemical shifts of (CH3CH2CH2NH3)2CuCl4 as a function of temperature obtained using 1H magic angle spinning nuclear magnetic resonance (MAS NMR) (inset: 1H MAS NMR spectrum of (CH3CH2CH2NH3)2CuCl4 at 300 K; spinning sidebands are marked with asterisks and open circles)
The paramagnetic Cu2+ ions in (CH3CH2CH2NH3)2CuCl4 were bonded with the inorganic layer through the N–H···Cl hydrogen bonds, and were paramagnetic, which directly affected the environment of 1H in NH3

Summary

Introduction

Hybrid organic-inorganic compounds provide a variety of opportunities for scientific study and technological application.[1,2,3,4,5,6,7] This broad range of materials allows the combination of organic and inorganic moieties with different properties within a single structure. Hybrid organic-inorganic compounds based on perovskite structures have been studied since 1976, but their potential as substitutes for perovskite has led to a recent surge in interest.[8,9] The perovskite-type layer compounds of the form (CnH2n+1NH3)2MCl4, where n=1, 2, 3, ···, and M=Mn, Fe, Cu, or Cd exhibit a wide variety of interesting structural phases.[10] Theoretical and experimental work has shown that structural phase transitions are related to changes in N-H···Cl hydrogen bond schemes, tilting of the MCl42- tetrahedral or MCl62- octahedral structure, and the orientation states of the alkyl chains for short chain compounds.

Methods

Results

Conclusion