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Ten ionic manganese(II) complexes of [EMIm]2[MnX2Y2] (EMIm=1‐ethyl‐3‐methylimidazolium ion; X, Y=Cl, Br or I) and [BnMIm]2[MnX2Y2] (BnMIm=1‐benzyl‐3‐methylimidazolium ion; X, Y=Cl, Br or I) types were synthesized and studied in terms of their thermal and photophysical properties. Complexes with [BnMIm]+ cation were found to exhibit higher crystallinity, owing to the aromatic π‐stacking, and superior photoluminescent quantum yields, promoted by the increased Mn⋅⋅⋅Mn distance. For complexes with chlorine and bromine ligands efficient tunability of photophysical parameters was demonstrated. Out of all complexes, [BnMIm]2[MnBr4] was found to have the highest photoluminescence quantum yield at room temperature (Φ=0.59). To highlight the importance of a large Mn⋅⋅⋅Mn distance for achieving high Φ values, a mixed‐anion analog of complex [BnMIm]2[MnBr4] was prepared, with the suggested formula of [BnMIm]4[MnBr4]Br2. The latter have shown a significant improvement in d–d absorption efficiency and a reduction in nonradiative deactivation, which led to an outstanding Φ value of 0.97. Finally, the optical band gap of [BnMIm]4[MnBr4]Br2 was estimated to describe its applicability as light‐emitting material. [ABSTRACT FROM AUTHOR]

New luminescent PtII complexes with the chiral counter anions [PtCl(tpy)](l‐Hta) (1‐L) and [PtCl(tpy)](dl‐Hta) (1‐DL; tpy = 2,2′:6′,2′′‐terpyridine; l‐H2ta = l‐tartaric acid; dl‐H2ta = racemic tartaric acid) were synthesized and their vapochromic behavior was evaluated. Single crystal X‐ray analysis revealed that the stacked square‐planar PtII molecules in anhydrous 1‐DL formed a one‐dimensional columnar structure with weak intermolecular Pt···Pt interactions, while in anhydrous 1‐L the PtII molecules were dimerized with Pt···Pt interactions to form a zig‐zag stacked column. These differences were attributed to the different hydrogen bonding in the dl‐ and l‐Hta– ions. The dihydrates of 1‐DL and 1‐L displayed near‐identical crystal structures with comparable emission spectra derived from 3π–π* ligand emission. Both dihydrates exhibited MeOH‐vapor‐induced dehydration to form the anhydrous complexes. These presented broad 3MMLCT emission (549 and 565 nm, respectively), affected by the degree of intermolecular Pt···Pt interactions. Vapochromic luminescent behavior of PtII complexes with a chiral counter anion and its racemic mixture were reported. Both chiral (1‐L) and racemic (1‐DL) complexes exhibited similar crystal structures and near‐identical emission (ligand 3π–π*) in their dihydrate forms. After dehydration, 1‐L presented lower energy emission maxima than 1‐DL, due to the different Pt···Pt interactions. [ABSTRACT FROM AUTHOR]

The reactions of quinoline-2-carbaldehyde (pyridine-2-carbonyl)hydrazone (HL) and [RuCl2(PPh3)3] in various solvents at different temperatures gave the three geometrical isomers trans(Cl,Cl)-, cis(Cl,Cl),trans(P,N)-, and trans(P,P)-[RuCl2(PPh3)2{HL-κ O(amide),κ N(imine)}] ( 1, 2, and 3, respectively) as well as a linkage isomer trans(P,P)-[RuCl2(PPh3)2{HL-κ N(imine),κ N(quin)}] ( 4). The molecular and crystal structures of 1- 4, together with both E and Z configurational isomers (with respect to the C=N double bond) of the free ligand HL, were determined by X-ray analysis. The ligand HL adopted a Z form and acted as a κ O(amide),κ N(imine) bidentate ligand in 1- 3, whereas it was an E isomer with a κ N(imine),κ N(quin) coordination mode in 4. The gradual thermal conversions of 1 to 2 and of 2 to 3 were observed in dichloromethane and ethanol, respectively, but an interconversion between 3 and 4 was not detected. In dichloromethane, all complexes have a reversible RuIII/II redox couple in the range 110-412 mV (vs. Ag/Ag+), and the redox potential was largely dependent on the coordination mode of HL and on the mutual configuration of the two PPh3 ligands. Such a potential shift can be interpreted as a combination of Cl-/amide O π-donor and PPh3/quinoline N π-acceptor orbital contributions to the RuII dπ orbitals [highest occupied molecular orbitals (HOMOs)]. Complexes 3 and 4 in acetonitrile showed a gradual spectral change, probably because of the substitution of the Cl- ligand by the acetonitrile solvent. In addition, 2- 4 showed solvatochromic behavior even in noncoordinating solvents that resulted from a blueshift of the metal-to-ligand charge-transfer (MLCT) transition band in polar solvents. These electrochemical and spectroscopic properties are also supported by DFT and time-dependent DFT (TD-DFT) calculations. [ABSTRACT FROM AUTHOR]