Pressure-and temperature induced phase transitions, piezochromism, NLC behaviour and pressure controlled Jahn–Teller switching in a Cu-based framework

Abstract

In-situ single-crystal diffraction and spectroscopic techniques have been used to study a previously unreported Cu-framework bis[1-(4-pyridyl)butane-1,3-dione]copper(II) (CuPyr-I). CuPyr-I was found to exhibit high-pressure and low-temperature phase transitions, piezochromism, negative linear...

Pressure-induced Jahn–Teller switch in the homoleptic hybrid perovskite [(CH3)2NH2]Cu(HCOO)3: orbital reordering by unconventional degrees of freedom

“…29 Such transitions have also been found in a relatively small number of coordination polymers composed of at least two different ligand species that disobey the spectrochemical series in the low-pressure phase, hence enabling the different ligand strengths to act as the driving force behind the PT. [30][31][32][33] Interestingly, in these coordination polymers a dramatic change in the magnetic structure was caused by the orbital reordering, 30,32,[34][35][36] in analogy with our predictions for [(CH 3 ) 2 NH 2 ]Cu(HCOO) 3 . To the best of our knowledge, pressure induced orbital reordering due to a JT switch has never been observed in a homoleptic coordination polymer.…”

Pressure Effects on 3dn (n=4, 9) Insulating Compounds: Long Axis Switch in Na3MnF6 not Due to the Jahn‐Teller Effect

“…Along this line, the existence of a switch of the JT axis recently put forward [66] for explaining the behavior of [(CH 3 ) 2 NH 2 ]Cu(HCOO) 3 under pressure is certainly doubtful due to the monoclinic symmetry of the lattice at ambient pressure. A similar situation holds for recent results [67] on the rhombohedral CuPyr‐I compound where the six ligands around Cu 2+ are not identical (two N and four O) a fact that is already against the existence of a JT effect.…”

Structural Chemistry of Metal–Organic Frameworks under Hydrostatic Pressures

“…For the graphene-like 2D-MOF Cu­(4hypymca), the application of pressure impacts its conductive properties, representing a good example where experiment guided theory reveals fascinating physicochemical properties at extreme conditions. One of the most complex high-pressure behaviors was arguably found for Cu­(bis­[1-(4-pyridyl)­butane-1,3-dione]), showing a phase transition, piezochromism, NLC behavior, and Jahn–Teller switching at high pressures . Altogether, these studies highlight the large variety of phenomena accessible under high pressures, gradually refining our chemical intuition of how pressure impacts material properties and point to future research opportunities.…”

“…One of the most complex high-pressure behaviors was arguably found for Cu(bis[1-(4-pyridyl)butane-1,3-dione]), showing a phase transition, piezochromism, NLC behavior, and Jahn− Teller switching at high pressures. 167 Altogether, these studies highlight the large variety of phenomena accessible under high pressures, gradually refining our chemical intuition of how pressure impacts material properties and point to future research opportunities. Until today, only a small fraction of MOFs has been investigated at high pressures, and the number of studies that look at high-pressure physicochemical properties such as optical, magnetic, and electronic properties is steadily increasing.…”