Thermally Induced trans‐to‐cis Isomerization and Its Photoinduced Reversal Monitored using Absorption and Luminescence: Cooperative Effect of Metal Coordination and Steric Substituent

Abstract

For ethene derivatives with large groups the cis‐isomer is often quite unstable and unavailable. Herein, we report an exception of two stable coordination complexes, (cis‐L)ZnCl2, starting from trans‐1,2‐bis(1‐R‐benzo[d]imidazol‐2‐yl)ethene (R=H, L1; R=CH3, L2) ligands under solvothermal condition (T ≥140 °C). Using the intensity of the absorption and luminescence spectra as probes we proposed its progressive cis‐to‐trans reversal upon irradiation with UV light, which was confirmed by powder X‐ray diffraction (PXRD). Similar results observed in the series of (cis‐L2)MIICl2 [M=Fe (4), Co (5), Ni (6)] demonstrate the universal strategy. The results of PXRD, NMR spectroscopy, ESI‐MS and DFT calculations support the above conclusion. NMR spectroscopy indicates that irradiation of 1 converts an optimized 71 % of the cis‐isomer to trans, whereas the free trans‐L1 ligand transforms to only 15 % cis‐isomer under similar conditions.

In Situ Metal‐Assisted Ligand Modification Induces Mn4 Cluster‐to‐Cluster Transformation: A Crystallography, Mass Spectrometry, and DFT Study

“…It indicates that [Mn 4 L x L′ 6− x ] intermediate fragments first form and then decompose. Our attempts to crystallize the intermediate fragments came to nothing, which is also consistent with the amorphous nature seen by PXRD …”

“…The times at which[ Mn 4 L x L' 6Àx ]i ncrease to their peak valuesr eveal an obvious order and time-dependent nature.I ti ndicates that [Mn 4 L x L' 6Àx ]i ntermediate fragments first form and then decompose.O ur attempts to crystallize the intermediate fragments came to nothing, which is also consistent with the amorphous nature seen by PXRD. [22,23]…”

Synthesis, Solid State, Solution and ESI‐MS Studies of Zinc(II) Cluster Complexes with a Branched Mixed Donor Thiolate Ligand

“…To complement solid state characterization, an acetonitrile solution of 1 was characterized by ESI‐MS. This very sensitive soft ionization technique is known to be widely suitable for rapid and sensitive study of complicated coordination systems and has been used to track the assembly and dissociation processes of a variety of multinuclear clusters . However, characterization of a mixture of complex ions with different metal‐to‐ligand ratios by ESI‐MS has some caveats.…”

Luminescence Switching of Organogold(I) Complexes between Aggregation‐induced Phosphorescence Enhancement and Aggregation‐caused Quenching by Balancing Auxiliary Ligands around the AuI Center

“…Previously, by integrating different functional auxiliary groups around specific metallic ions, we modulated their luminescent performance [13] and turned on the luminescence by trans-to-cis isomerization. [14] Herein, the multi-rotor structural phosphine ligand L1 ([1,1':2',1'':4'',1'''-quaterphenyl]-2yldiphenylphosphane) [15] was chosen to link with Au I , affording AIPE-active L1AuCl (1), of which the luminescent intensity increasement was dependent on poor solvent contents in the mixed solvents. Then, using coplanar L2 (9-ethynylanthracene) replacing Cl À in 1 (Scheme 1) provided ACQ-active 2 (C 14 H 9 C�CAuL1), [16] which exhibited bright blue with the photoluminescence quantum yield (Φ) up to 50.70% in dilute solution, but weak emission (Φ = 2.85%) in solid state.…”