Natalia V. Pervukhina

Coordination of Phenylsulfinate PhSO2— to Mo3MS44+ Clusters (M = Ni, Pd)

Reaction of heterometal cuboidal clusters [Mo3(MCl)S4(H2O)9]3+ (M = Ni, Pd) with PhSO2Na in aqueous HCl leads to the substitution at Ni or Pd to give the [Mo3(M(PhSO2))(H2O)9—xClx](3—x)+species, isolated as supramolecular adducts with cucurbituril (Cuc) [Mo3(Ni(PhSO2))S4Cl1.17(H2O)7.83][Mo3(Ni(PhSO2))S4Cl2.22(H2O)6.78]Cl2.61 · Cuc · 15H2O (1) and [Mo3(Pd(PhSO2))S4Cl1.12(H2O)7.88][Mo3(Pd(PhSO2))S4Cl2.29(H2O)6.71]Cl2.59 · Cuc · 11H2O (2), respectively. Crystal structure of 1 and 2 was determined, revealing that the PhSO2 is coordinated via its sulfur atom (Ni — S 2.182 A, Pd — S 2.305 A). The structure of these isostructural compounds is built from triple aggregates {(cluster)(Cuc)(cluster)} united into zigzag chains via hydrogen bonds between coordinated PhSO2 and H2O ligands. n n n nDie Koordination von Phenylsulfinat PhSO2— an Mo3MS44+ Cluster (M = Ni, Pd). n n n nDie Reaktion von kubanartigen Clustern [Mo3(MCl)S4(H2O)9]3+ (M = Ni, Pd) mit PhSO2Na in Salzsaure fuhrt zum Ligandenaustausch an Ni oder Pd. Dabei entstehen die Komplexe [Mo3(M(PhSO2))(H2O)9—xClx](3—x)+, die sich als Supramolekularaddukte mit Kukurbituril (Cuc), [Mo3S4Ni(PhSO2)Cl1.17(H2O)7.83][Mo3S4Ni(PhSO2)Cl2.22(H2O)6.78]Cl2.61 · Cuc · 15H2O (1), [Mo3(Pd(PhSO2))S4Cl1.12(H2O)7.88][Mo3(Pd(PhSO2))Cl2.29(H2O)6.71]Cl2.59 · Cuc · 11H2O (2) isolieren lassen. Die Kristallstrukturen der isostrukturellen Komplexe 1 und 2 wurden bestimmt. Der Ligand PhSO2— ist durch das Schwefelatom koordiniert (Ni — S 2.175 A, Pd — S 2.305 A). Die Struktur zeigt, dass zwei Cluster- und ein Kukurbirurilmolekul Addukte vom Typ {(Cluster)(Kukurbituril)(Cluster)} bilden, die sich weiter durch Wasserstoffbrucken zwischen PhSO2 und koordiniertem H2O zu Zickzackketten verknupfen.

Zinc(II) complexes with an imidazolylpyridine ligand: luminescence and hydrogen bonding

ZnLCl and [H2L]2[ZnCl4], based on 2-(1-hydroxy-4,5-dimethyl-1H-imidazol-2-yl)pyridine (HL), have been synthesized. There is a short intraionic O–H···N hydrogen bond between the hydroxyimidazolyl and pyridyl of H2L+ cations (N···O 2.608(2)u2009Å) in the structure of [H2L]2[ZnCl4]. The formation of this rather strong hydrogen bond is confirmed by IR spectroscopy through a broad band at 3200–2200u2009cm−1 and a band at 1655u2009cm−1. HL crystallizes in the form of a hemihydrate, HL·0.5H2O. HL assemble into infinite helical chains due to N–H···O intermolecular hydrogen bonds between the NH of imidazole and O of the N-oxide (O···N 2.623(2)u2009Å). An unusual mid-IR pattern with three broad bands at 3373, 2530, and 1850u2009cm−1 is typical for strong hydrogen bonds, explained by resonance-assisted hydrogen bonding occurring in the helical chains. On cooling to 5u2009K, noticeable changes in the IR spectra of [H2L]2[ZnCl4] and HL·0.5H2O were observed. ZnLCl and [H2L]2[ZnCl4] exhibit bright photoluminescence with maxima of emission at 458u2009nm (for ZnLCl) and 490u2009nm (for [H2L]2[ZnCl4]). Graphical Abstract

Excitation-Wavelength-Dependent Emission and Delayed Fluorescence in a Proton-Transfer System

Manipulating the relaxation pathways of excited states and understanding mechanisms of photochemical reactions present important challenges in chemistry. Here we report a unique zinc(II) complex exhibiting unprecedented interplay between the excitation-wavelength-dependent emission, thermally activated delayed fluorescence (TADF) and excited state intramolecular proton transfer (ESIPT). The ESIPT process in the complex is favoured by a short intramolecular OH⋅⋅⋅N hydrogen bond. Synergy between the excitation-wavelength-dependent emission and ESIPT arises due to heavy zinc atom favouring intersystem crossing (isc). Reverse intersystem crossing (risc) and TADF are favoured by a narrow singlet-triplet gap, ΔEST ≈10u2005kJu2009mol-1 . These results provide the first insight into how a proton-transfer system can be modified to show a synergy between the excitation-wavelength-dependent emission, ESIPT and TADF. This strategy offers new perspectives for designing ESIPT and TADF emitters exhibiting tunable excitation-wavelength-dependent luminescence.