Exploring the influence of polymorphism and chromophore co-ligands on linkage isomer photoswitching in [Pd(bpy4dca)(NO₂)₂]

Abstract

The polymorphic Pd(II)-nitrite complex [Pd(bpy4dca)(NO2)2] (1) (bpy4dca = 2,2’-bipyridine-4,4’-dicarboxylic acid methyl ester) is shown to undergo photoinduced nitro → nitrito linkage isomer switching in two crystal forms, to varying excited...

Impact of Cis–Trans Isomerism on Crystal Packing and Photo-Activity of a Cobalt(III) Room-Temperature Photoswitch

“…Finally, based on the TDDFT computational results obtained for the cis and trans forms, in both cases, there are low-energy electronic transitions, similar in nature to that reported in the literature, ,, which may lead to the Co–N bond breaking, thus to further light-induced switching. For example, in the case of the cis -Co , the HOMO–2, HOMO–1 and LUMO, LUMO+1 pairs of occupied and unoccupied orbitals exhibit bonding and antibonding character, respectively (Supporting Information).…”

“…As far as the ambidentate ligands are concerned, the NO 2 group has caught particular attention. It may adopt up to nine different binding modes, and some of which can interconvert from one to another upon certain conditions. − Up-to-date, numerous photoswitchable nitro transition-metal coordination systems have been reported. ,− Most of them, however, are characterized by partial nitro-to-nitrito photoconversion, which is observed at rather low temperatures, i.e., below 250 K. ,,,− There are although a few examples of high conversion materials of this kind, or complexes which work at higher temperatures. For instance, Hatcher introduced a 100%-photoswitchable [Pd­(Bu 4 dien)­(η 1 -NO 2 )]­[BPh 4 ] complex for which the photo-induced linkage isomer (PLI) was detected in a single crystal up to 260 K under continuous illumination.…”

Photogeneration of Several Linkage Isomers and Investigation of Forward and Backward Nitro-Nitrito Isomerization Processes in a Palladium Complex

“…This can be prevented if the molecular movement during the reaction is relatively small and the atoms forming photoproduct occupy similar positions in a crystal, if there is a lot of free space around reaction center and/or if the crystal has a high elasticity. , In the studied cases, the volume of the unit cell changed after irradiation by 1.3, 1.0, 1.1, and 0.5% for Cr at 10 K, Cr , Co , and Rh at 150 K, respectively. These relatively small changes suggest rather little strain in the crystals when nitrito isomers are formed. , Crystal structures data gathered in Table S1 show that in case of Cr and Rh the quality of the crystal is maintained during irradiation, e.g., for crystal of Rh the R int value increased by 0.83% point (from 5.34 to 6.17%) and the number of observed reflections decreased by about 0.65% (from 7502 to 7452 reflections) after irradiation for 240 min. In the case of Co , however, a strong decrease of the crystal quality was observed after crystal irradiation and relaxation back to the ground state, i.e., the R int value increased by 8.86% point (from 5.42% through 7.23% after irradiation to 14.28% after relaxation) and the number of observed reflections decreased by 39% (from 7125 through 5526 to 4322 reflections).…”

“…These relatively small changes suggest rather little strain in the crystals when nitrito isomers are formed. 3,45 Crystal structures data gathered in Table S1 show that in case of Cr and Rh the quality of the crystal is maintained during irradiation, e.g., for crystal of Rh the R int value increased by 0.83% point (from 5.34 to 6.17%) and the number of observed reflections decreased by about 0.65% (from 7502 to 7452 reflections) after irradiation for 240 min. In the case of Co, however, a strong decrease of the crystal quality was observed after crystal irradiation and relaxation back to the ground state, i.e., the R int value increased by 8.86% point (from 5.42% through 7.23% after irradiation to 14.28% after relaxation) and the number of observed reflections decreased by 39% (from 7125 through 5526 to 4322 reflections).…”

Uncovering the role of non-covalent interactions in solid-state photoswitches by non-spherical structure refinements with NoSpherA2

“…In future we plan to extend this approach to more complicated systems, e.g. crystals that only reach partial excitation at their maximum irradiation time, 22,45 and whose diffraction power becomes considerably limited as a result of light damage on irradiation. 46…”