Photophysical and DFT Studies of Cationic Ag(I) Complexes with Thiosemicarbazides Derived from p‐Toluenesulfohydrazide

Abstract

Reactions of p-toluenesulfohydrazide with R-isothiocyanates afford new ligands containing both the sulfonamide and thiosemicarbazide moieties (L R : R= cyclohexyl (Cy) or phenyl (Ph)). L R reacts with AgNO 3 in EtOH in a 2:1 M ratio leading to formation of colourless Ag(I) complexes of general formula [Ag(L R ) 2 ]NO 3 . The crystal structure of a representative complex was determined by crystallographic studies and shows the Ag(I) coordinated by two thiosemicarbazide ligands in a Smonodentate coordination mode along with a significant interaction with a nitrate counter-ion in a bent geometry.Photophysical studies show that both the free ligands and complexes are essentially non-luminescent at room temperature. At 77 K and glassy media, the silver complexes exhibit a luminescence band in the visible-light region. Besides, experimental and theoretical analyses suggest the population of the triplet state of these complexes after electronic excitation at around 250 nm. Overall, it was verified that the observed emission of the Ag(I) complexes can be attributed to 3 MLCT radiative decay and that the silver complex with L Ph shows a higher intensity emission than the complex with L Cy .

Gold(I) and Silver(I) Complexes Containing Hybrid Sulfonamide/Thiourea Ligands as Potential Leishmanicidal Agents

“…There were no significant changes in the bands observed in relation to HL1-6 free ligands; however, the molar absorptivities registered were different after complexation. The first band observed in the spectra can be attributed to π→π* intraligand transitions, while the second band, according to theoretical calculations obtained for similar silver(I) complexes [ 22 ], is characteristic of charge transfer transitions MLTC (metal-to-ligand charge transfer), due to the electronic configurations of Ag(I) and Au(I).…”

“…The synthesis and spectroscopic characterization of HL R ligands by FTIR and 1 H NMR has already been reported and will not be the focus of the present work [ 22 , 32 , 33 , 34 ]. Herein, HL R (R = F, Cl, NO 2 and Alil) were further analyzed by other methods, including crystallographic determination.…”

“…Based on the interest in developing new drugs for Leishmaniasis, biological studies were initiated by carrying out in vitro tests to evaluate the cell viability (cytotoxicity) of free ligands (H L1-6 ) and Ag3 – Ag4 and Au1 – Au6 complexes against kidney cells of the African green monkey ( Vero ). In addition to these compounds, the [Ag(HL1 Ch ) 2 ]NO 3 ( Ag1 ) and [Ag(HL2 Ph ) 2 ]NO 3 ( Ag2 ) complexes, obtained in a previous work, were included in the test [ 22 ]. Through this test, it was possible to determine the CC 50 values (inhibitory concentration for the viability of 50% of the cells).…”

“…The reagents, p -toluenesulfohydrazide, cyclohexyl isothiocyanate, phenyl isothiocyanate, 4-fluorophenyl isothiocyanate, 4-chlorophenyl isothiocyanate, 4-nitrophenyl isothiocyanate, allyl isothiocyanate, AgNO 3 and [AuCl(DMS)] were obtained commercially (Sigma Aldrich, Cotia, Brazil). HL1 Ch , HL2 Ph , [Ag(HL1 Ch ) 2 ]NO 3 ( Ag1 ) and [Ag(HL2 Ph ) 2 ]NO 3 ( Ag2 ) were obtained as previously reported [ 22 ].…”

Efficient doped and non-doped light-emitting diodes based on a TADF-emitting Cu4Br4 cluster

“…[13][14][15][16][17][18][19][20][21] Moreover, the heavy atom effect (HAE) exhibited by these clusters can lead to significant SOCs between the lowest triplet and singlet states, thereby facilitating intersystem crossing (ISC) and phosphorescence processes, and the high rigidity of the cluster structure effectively inhibits the photothermal decomposition of Cu(I) and the quenching of the excited state caused by the Jahn-Teller distortion. [22][23][24][25] These attributes of copper(I)-halide clusters make them potential high-efficiency EL emitters. Nonetheless, copper(I)-halide clusters often come with significant drawbacks when it comes to the fabrication of efficient EL devices.…”