N-Heterocyclic Donor- and Acceptor-Type Ligands Based on 2-(1H-[1,2,3]Triazol-4-yl)pyridines and Their Ruthenium(II) Complexes

Abstract

New 2-(1H-[1,2,3]triazol-4-yl)pyridine bidentate ligands were synthesized as bipyridine analogs, whereas different phenylacetylene moieties of donor and acceptor nature were attached at the 5-position of the pyridine unit. The latter moieties featured a crucial influence on the electronic properties of those ligands. The N-heterocyclic ligands were coordinated to ruthenium(II) metal ions by using a bis(4,4'-dimethyl-2,2'-bipyridine)ruthenium(II) precursor. The donor or acceptor capability of the 2-(1H-[1,2,3]triazol-4-yl)pyridine ligands determined the quantum yield of the resulting ruthenium(II) complexes remarkably. Separately, 2-([1,2,3]triazol-4-yl)pyridine ligands are known to be potential quenchers, but using these new ligand systems led to room temperature emission of the corresponding ruthenium(II) complexes. The compounds have been fully characterized by elemental analysis, high-resolution ESI mass spectrometry, (1)H and (13)C NMR spectroscopy, and X-ray crystallography. Theoretical calculations for two ruthenium(II) complexes bearing a donor and acceptor unit, respectively, were performed to gain a deeper understanding of the photophysical behavior.

Progress and Challenges in the Calculation of Electronic Excited States

“…In general, it is only the experimental UV absorption spectrum or emission energies that are compared with the theory. Our work on Ru, [197][198][199][200] Ir, [201,202] Pt [203,204] and Zn [205] complexes, and that of many other groups, see for example refs. [206][207][208][209], have found that, astonishingly, TD-DFT can be in reasonable agreement with the experiment as long as a judicious selection of functionals/basis is done and solvent effects are included.…”

“…[206][207][208][209], have found that, astonishingly, TD-DFT can be in reasonable agreement with the experiment as long as a judicious selection of functionals/basis is done and solvent effects are included. [198,202,206] A recent study on the trans(Cl)-Ru(bpy)Cl 2 (CO) 2 complex shows that functionals bearing intermediate amounts of exact exchange, such as M06, PBE0 and B3LYP, can deliver energies comparable to RASPT2 ones. [210] The question that naturally arises is, which functionals perform better in a particular situation?…”

Synthesis and NMR Analysis of 1,4‐Disubstituted 1,2,3‐Triazoles Tethered to Pyridine, Pyrimidine, and Pyrazine Rings

“…The quantities used in the above procedure, spectral and analytical data are given below. Phenyl-1H-1,2,3-triazol-4-yl) 1-(4-Cyanophenyl)-1H-1,2,3-triazol-4-yl]pyridine (4Ia, R = CN [8] General Procedure for the Synthesis of Triazoles 5: A mixture of azide 1C-1E and phenylacetylene 2(f-j,l-n) was cooled to ca. 10°C in an ice-water bath, and CuBr(PPh 3 ) 3 was added to the stirred mixture.…”

“…[5] In coordination chemistry, for example, architectures containing this heterocycle have been developed as monodentate and polydentate nitrogen ligands. Special attention has been given to (2-pyridyl)-and more flexible (2-picolyl)-1,2,3-triazoles, [6,7] because they are viewed as surrogates for the well-known 2,2Ј-bipyridine [8] and bis(heterocycle)methane ligands, respectively.…”

Towards Water Soluble Mitochondria-Targeting Theranostic Osmium(II) Triazole-Based Complexes

“…We, and others, have paid particular attention to the use of copper-catalysed coupling of alkynes and azides to form 1,2,3-triazole-based ligands [7][8][9][10] and have investigated the photophysical properties of their resultant complexes. A significant number of reports have appeared detailing the photophysical and photochemical properties of triazole-based complexes of Re(I), Ru(II) and Ir(III) [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25]. Examples of triazole-containing complexes of osmium(II)…”