A. Paderina, R. Ramazanov, R. Valiev, C. Müller and E. Grachova, So Close, Yet so Different: How One Donor Atom Changes Significantly the Photophysical Properties of Mononuclear Cu(I) Complexes, Inorg. Chem., (2022) DOI: 10.1021/acs.inorgchem.2c01145

The replacing the nitrogen atom with the heavier phosphorus atom in isostructural diimine- and phosphinine-based Cu(I) complexes results in a significant change in the lifetime of the excited state and emission energy due to the 'heavier pnictogen atom' effect.

A.V. Paderina, I.O. Koshevoy and E.V. Grachova, Keep it tight: a crucial role of bridging phosphine ligands in the design and optical properties of multinuclear coinage metal complexes, Dalton Trans., (2021) DOI: 10.1039/D1DT00749A

Stereochemical properties and flexibility of organic spacer in oligodentate phosphine ligand and spatial separation of phosphorus atoms one relative to other regulate the composition and molecular architecture of multinuclear compounds of coinage metals.

This article is part of the themed collections:
2021 Frontier and Perspective articles and Dalton Transactions HOT Articles

D.O. Kozina, J.R. Shakirova, E.E. Galenko, V.V. Porsev, V.V. Gurzhiy, A.F. Khlebnikov, S.P. Tunik, Unusual Reactivity and Photophysical Properties of the Pt(II) Pincer Complexes Containing 6,6'-diphenyl-2,2'-bipyridine ligands, Eur. J. Inorg. Chem., (2021) DOI: 10.1002/ejic.202000827

A series of novel 6,6'-diphenyl-2,2'-bipyridine ligands modified with the substituents at phenyl and bipyridine moieties have been prepared and used in the synthesis of pincer platinum chloride complexes 1–3, [Pt(NNC-R)Cl]. Reactions of the obtained compounds with triphenylphosphine proceed through unusual pathway, which gives the [Pt(NNC–R)(PPh₃)₂Cl] products containing two phosphine ligands, with the chloride retained in coordination sphere and diphenyl-bipyridine fragment coordinated in η¹-mode through metalation of a pyridine ring. The complexes 1–3 are phosphorescent in dichloromethane solution and in solid state. Their photophysical characteristics were determined and analyzed by DFT calculations, which gave assignment of emissive excited state character with the major contribution from the intraligand charge transfer (³ILCT, Ph-bipyridine) and ligand centered (³LC, bipyridine fragment) transitions.

S. Petrovskii, V. Khistiaeva, A. Sizova, V. Sizov, A. Paderina, I. Koshevoy, K. Monakhov, E. Grachova, Hexavanadate-Organogold(I) Hybrid Compounds: Synthesis by the Azide-Alkyne Cycloaddition and Density Functional Theory Study of an Intriguing Electron Density Distribution, Inorg. Chem., (2020) DOI: 10.1021/acs.inorgchem.0c02621

The fully-oxidized Lindqvist-type hexavanadate compounds decorated by phosphine-derivatized Au(I) moieties orientated in a transoid fashion have been prepared by azide-alkyne cycloaddition reactions and characterized by various techniques. Electronic structure calculations unveil the potential of these model hybrid junctions for application in controlled charge transport experiments on substrate surfaces.

V.V. Khistiaeva, A.S. Melnikov, S.O. Slavova, V.V. Sizov, G.L. Starova, I.O. Koshevoy, and E.V. Grachova, Heteroleptic β-diketonate Ln(III) complexes decorated by pyridyl substituted pyridazine ligand: synthesis, structure and luminescent properties, Inorg. Chem. Front., (2018) DOI: 10.1039/C8QI00712H

A series of mononuclear heteroleptic complexes [Ln(tta)₃(dppn)] (Ln = Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu; Htta = thenoyltrifluoroacetone; dppn = 3,6-di(2-pyridyl)pyridazine) have been synthesized. The crystal structures reveal that the dppn ligand coordinates to Ln(III) in an asymmetrical manner.
It has been found that complexes of Nd, Sm, Eu, and Yb showed intense metal-centred emissions in the solid state under UV excitation.
A careful examination of the emission spectrum of [Eu(tta)₃(dppn)] suggests that a powder sample of the complex can contain two isomers with somewhat different symmetries of the environment of the Eu(III) centre.
The mechanism for the emission of the Ln(III) complexes was investigated by TDDFT calculations and the results confirmed the conclusion made on the basis of experimental data regarding the likely pathway of energy transfer from the chromophore centre to the emissive level of Ln(III).

A.A. Penney, V.V. Sizov, E.V. Grachova, D.V. Krupenya, V.V. Gurzhiy, G.L. Starova and S.P. Tunik, Aurophilicity in Action: Fine-tuning the Gold(I)–Gold(I) Distance in the Excited State to Modulate the Emission in a Series of Dinuclear Homoleptic Gold(I)–NHC complexes, Inorg. Chem., (2016) DOI: 10.1021/acs.inorgchem.5b02722

A series of dinuclear NHC carbene homoleptic Au(I) complexes based on the benzimidazol-2-ylidene scaffold with alkyl spacers of varying length was prepared. Bromide-binding behavior of the complexes was qualitatively probed in solution by means of NMR and luminescence spectroscopy.
On the basis of theoretical investigations, it was proposed that emission in solution originates from the binding of solvent molecules or bromide counterions by the triplet excited state of the cations. For the first time, a detailed DFT study established a clear link between bromide coordination to the Au(I) centers and the strength of the intracationic aurophilic interaction in the triplet excited state.

A.A. Beljaev, D.V. Krupenya, E.V. Grachova, V.V. Gurzhiy, A.S. Melnikov, P.Yu. Serdobintsev, E.S. Sinitsyna, E.G. Vlakh, T.B. Tennikova and S.P. Tunik, Supramolecular Au^I-Cu^I complexes as new luminescent labels for covalent bioconjugation, Bioconjugate Chem., (2016) DOI: 10.1021/acs.bioconjchem.5b00563

Two new supramolecular Au(I)-Cu(I) cluster complexes with highly reactive aldehyde and isothiocyanate groups have been synthesized. The both compounds obtained demonstrated bright emission in solution with the excited-state lifetime in microsecond domain both under single- and two-photon excitation.
It has been found that the both complexes form the covalent conjugates with proteins of different molecular size (soybean trypsin inhibitor, human serum albumin, rabbit anti-HSA antibodies). The conjugates demonstrated a high level of the phosphorescent emission from the covalently bound label, excellent solubility, and high stability in physiological media.
The measured biological activity of one of the labeled model proteins clearly showed that introduced label did not prevent the biorecognition and specific protein-protein complex formation that was extremely important for the application of the conjugates in biomolecular detection and imaging.

A.I. Solomatina, D.V. Krupenya, V.V. Gurzhiy, I. Zlatkin, A.P. Pushkarev, M.N. Bochkarev, N.A. Besley, E. Bichoutskaia, S.P. Tunik, Cyclometallated platinum(II) complexes containing NHC ligands; synthesis, characterization, photophysics and their application as emitters in OLEDs, Dalton Trans., (2015) DOI: 10.1039/C4DT03106G

A series of NHC carbene Pt(II) complexes based on cyclometallated phenylpyridine and benzoquinoline ligands have been synthesized. The complexes display moderate to strong phosphorescence in solution and in the solid state, which is related to the metal center modulated intraligand pp* transitions located at the aromatic system of the cyclometallated ligands with some contribution of the MLCT excited state. The nature of emission observed was also studied using the DFT and TDDFT approaches which confirmed the assignment mentioned above.
The compounds obtained were also used to prepare OLED devices, which display good luminance efficiency emitting in the green area of the visible spectrum.

I.O. Koshevoy, C.-L. Lin, A.J. Karttunen, J. Janis, M. Haukka, S.P. Tunik, P.-T. Chou, T.A. Pakkanen, Highly luminescent octanuclear Au^I-Cu^I clusters adopting two structural motifs: The effect of aliphatic alkynyl ligands, Chem. Eur. J., (2011) DOI: 10.1002/chem.201101936

A family of novel intensely luminescent octanuclear Au(I)-Cu(I) clusters bearing aliphatic and hydroxyl-aliphatic alkynyl ligands and the bridging diphosphines was effectively synthesized by self-assembly reactions of the homoleptic (AuC2R)n precursors with stoichiometric amounts of PPh₂C₆H₄PPh₂ phosphine and Cu(I) ion.
Steric bulkiness of the alkynyl ligands and intramolecular hydrogen bonding are suggested to play an important role in stabilizing the different type of cluster structural motif. All the complexes exhibit intense photoluminescence in solution with emission parameters that depending on the geometrical arrangement of the octanuclear metal core.