Ruthenium(II) Photosensitizers of Tridentate Click-Derived Cyclometalating Ligands: A Joint Experimental and Computational Study

Recent developments in the synthesis and applications of terpyridine-based metal complexes: a systematic review

Terpyridine-based metal complexes have emerged as versatile and indispensable building blocks in the realm of modern chemistry, offering a plethora of applications spanning from materials science to catalysis and beyond. This comprehensive review article delves into the multifaceted world of terpyridine complexes, presenting an overview of their synthesis, structural diversity, and coordination chemistry principles. Focusing on their diverse functionalities, we explore their pivotal roles in catalysis, supramolecular chemistry, luminescent materials, and nanoscience. Furthermore, we highlight the burgeoning applications of terpyridine complexes in sustainable energy technologies, biomimetic systems, and medicinal chemistry, underscoring their remarkable adaptability to address pressing challenges in these fields. By elucidating the pivotal role of terpyridine complexes as versatile building blocks, this review provides valuable insights into their current state-of-the-art applications and future potential, thus inspiring continued innovation and exploration in this exciting area of research.

Tuning Photoredox Catalysis of Ruthenium with Palladium: Synthesis of Heterobimetallic Ru-Pd Complexes That Enable Efficient Photochemical Reduction of CO2

New Ru-Pd heterobimetallic complexes were synthesized and structurally characterized utilizing 6,6″-bis(phosphino)-2,2':6',2″-terpyridine as a scaffold for the metal-metal bond. The dicationic Ru-Pd complex was found to exhibit high catalytic activity as a photocatalyst for photochemical reduction of CO2 to CO under visible light irradiation. This study established a new design of transition metal catalysts that tune photoredox catalysis with metalloligands.

Computational investigations of click-derived 1,2,3-triazoles as keystone ligands for complexation with transition metals: a review

In recent years, metal complexes of organo 1,2,3-triazole click-derived ligands have attracted significant attention as catalysts in many chemical transformations and also as biological and pharmaceutical active agents. Regarding the important applications of these metal-organo 1,2,3-triazole-based complexes, in this review, we focused on the recently reported investigations of the structural, electronic, and spectroscopic aspects of the complexation process in transition metal complexes of 1,2,3-triazole-based click ligands. In line with this, the coordination properties of these triazole-based click ligands with transition metals were studied via several quantum chemistry calculations. Moreover, considering the complexation process, we have presented comparative discussions between the computational results and the available experimental data.

An unexpected journey from highly tunable phosphorescence to novel photochemistry of 1,2,3-triazole-based complexes

Complexes containing the humble 1,2,3-triazole ring moiety have enabled access to highly tunable with efficient phosphorescence but have also in facilitated access to novel photoreactive excited states yielding highly unusual photochemical reactivity.

Efficient and straightforward click synthesis of structurally related dendritic triazoles

Structurally related triazolic dendrimers were efficiently synthesized applying CuAAC reaction.

Unusual dimer formation of cyclometalated ruthenium NHC p-cymene complexes

Abstraction of a chloride ion in p-cymene ruthenium(ii) complexes bearing cyclometalated NHC ligands selectively leads to the formation of mono-ion-bridged ruthenium dimers.

Excited state decay of cyclometalated polypyridine ruthenium complexes: insight from theory and experiment

This perspective article tackles the open question why cyclometalated polypyridine ruthenium(ii) complexes typically only emit very weakly at room temperature and delivers answers beyond the standard schemes involving ³MC and tunneling decay channels.

Energy transfer and formation of long-lived 3MLCT states in multimetallic complexes with extended highly conjugated bis-terpyridyl ligands

Multimetallic complexes with extended conjugated ligands show efficient energy transfer to the lowest excited states and prolonged Fe(ii) ³MLCT lifetimes.

The btp [2,6-bis(1,2,3-triazol-4-yl)pyridine] binding motif: a new versatile terdentate ligand for supramolecular and coordination chemistry

Ligands containing the btp [2,6-bis(1,2,3-triazol-4-yl)pyridine] motif have appeared with increasing regularity over the last decade. This class of ligands, formed in a one pot ‘click’ reaction, has been studied for various purposes, such as for generating d and f metal coordination complexes and supramolecular self-assemblies, and in the formation of dendritic and polymeric networks, etc. This review article introduces btp as a novel and highly versatile terdentate building block with huge potential in inorganic supramolecular chemistry. We will focus on the coordination chemistry of btp ligands with a wide range of metals, and how it compares with other classical pyridyl and polypyridyl based ligands, and then present a selection of applications including use in catalysis, enzyme inhibition, photochemistry, molecular logic and materials, e.g. polymers, dendrimers and gels. The photovoltaic potential of triazolium derivatives of btp and its interactions with anions will also be discussed.

New ruthenium bis(terpyridine) methanofullerene and pyrrolidinofullerene complexes: synthesis and electrochemical and photophysical properties

A series of terpyridine (tpy) methanofullerene and pyrrolidinofullerene dyads linked via p-phenylene or p-phenyleneethynylenephenylene (PEP) units is presented. The coordination to ruthenium(II) yields donor-bridge-acceptor assemblies with different lengths. Cyclic voltammetry and UV-vis and luminescence spectroscopy are applied to study the electronic interactions between the active moieties. It is shown that, upon light excitation of the ruthenium(II)-based (1)MLCT transition, the formed (3)MLCT state is readily quenched in the presence of C60. The photoinduced dynamics have been studied by transient absorption spectroscopy, which reveals fast depopulation of the (3)MLCT (73-406 ps). As a consequence, energy transfer occurs, populating a long-lived triplet state, which could be assigned to the (3)C60* state.

Facile thermodynamic conversion of a linear metallopolymer into a self-assembled hexameric metallomacrocycle

A dimetallo-macrocyclic hexamer has been quantitatively synthesized by the thermal disassembly/reassembly of a heteronuclear polymer.

Reversing the relative 3MLCT–3MC order in Fe(ii) complexes using cyclometallating ligands: a computational study aiming at luminescent Fe(ii) complexes

Positioning two cyclometallating rings on the periphery of tridentate ligands has allowed us to design for the first time an iron(ii) complex bearing the lowest triplet state of MLCT nature.

Thiocyanate-free cyclometalated ruthenium(II) sensitizers for DSSC: a combined experimental and theoretical investigation

In an effort to bring out efficient thiocyanate-free dyes for dye sensitized solar cells (DSSC) we have designed, synthesized and characterized four novel cyclometalated ruthenium(II) dyes (M1 to M4) with superior photochemical properties. All dyes contain terpyridyl ligands (TPY) with carboxylic acids as anchoring groups and cyclometalated ligand (TPY-C) with substituents for fine tuning the electronic properties. We obtain a broad absorption band which extends up to 725 nm due to metal to ligand charge transfer (MLCT) when donating groups are used, which slightly blue-shifts when a withdrawing group is used. In addition to the CT, small HOMO-LUMO gaps are obtained from electrochemical measurements which indicate characteristics of an ideal sensitizer. All four dyes were used as sensitizers for DSSC and photoelectrochemical measurements were carried out. Reasonably good efficiency (7.1%) has been achieved for . We have carried out periodic-DFT studies of these dyes adsorbed on the (TiO2)38 cluster. They revealed that, in bidentate bridging mode the dyes preferably bind with the help of two carboxylic groups onto the TiO2. To the best of our knowledge we are the first to do DFT studies of thiocyanate free cyclometalated ruthenium(ii) dyes tethered to TiO2.

Tuning the electronic coupling in cyclometalated diruthenium complexes through substituent effects: a correlation between the experimental and calculated results

A common bridging ligand, 3,3',5,5'-tetrakis(N-methylbenzimidazol-2-yl)biphenyl, and four terpyridine terminal ligands with various substituents (amine, tolyl, nitro, and ester groups) have been used to synthesize ten cyclometalated diruthenium complexes 1(2+) -10(2+) . Among them, compounds 1(2+) -6(2+) are redox nonsymmetric, and others are symmetric. These complexes show two Ru(III/II) processes and an intervalence charge transfer (IVCT) transition in the one-electron oxidized state. The potential separation (ΔE) of 1(2+) -10(2+) has been correlated to the energy difference ΔG(0) , the energy of the IVCT band Eop , and the ground-state delocalization coefficient α(2) . Time-dependent (TD)DFT calculations suggest that the absorptions in the visible region of 1(2+) -6(2+) are mainly associated with the metal-to-ligand charge-transfer transitions from both ruthenium ions and to both terminal ligands and the bridging ligand. However, the energies of these transitions vary significantly. DFT calculations have been performed on 1(2+) -6(2+) and 1(3+) -6(3+) to give information on the electronic structures and spin populations of the mixed-valent compounds. The TDDFT-predicted IVCT excitations reproduce well the experimental trends in transition energies. In addition, three monoruthenium complexes have been synthesized for a comparison study.

Synthesis, photovoltaic performances and TD-DFT modeling of push-pull diacetylide platinum complexes in TiO2 based dye-sensitized solar cells

In this joint experimental-theoretical work, we present the synthesis and optical and electrochemical characterization of five new bis-acetylide platinum complex dyes end capped with diphenylpyranylidene moieties, as well as their performances in dye-sensitized solar cells (DSCs). Theoretical calculations relying on Time-Dependent Density Functional Theory (TD-DFT) and a range-separated hybrid show a very good match with experimental data and allow us to quantify the charge-transfer character of each compound. The photoconversion efficiency obtained reaches 4.7% for 8e (see TOC Graphic) with the tri-thiophene segment, which is among the highest efficiencies reported for platinum complexes in DSCs.