Synthesis, DNA-binding, DNA-photocleavage and antioxidant activity of ruthenium(II) complex containing triazine ring ligand: [Ru(dmb)2(pdta)](ClO4)2

Modulation of the Excited States of Ruthenium(II)-perylene Dyad to Access Near-IR Luminescence, Long-Lived Perylene Triplet State and Singlet Oxygen Photosensitization

Herein, we present a novel ruthenium(II)-perylene dyad (RuPDI-Py) that combines the photophysical properties of pyrrolidine-substituted perylene diimide (PDI-Py) and the ruthenium(II) polypyridine complex [Ru(phen)3]2+. A comprehensive study of excited-state dynamics was carried out using time-resolved and steady-state methods in a dimethyl sulfoxide solution. The RuPDI-Py dyad demonstrated excitation wavelength-dependent photophysical behavior. Upon photoexcitation above 600 nm, the dyad exclusively exhibits the near-infrared (NIR) fluorescence of the 1PDI-Py state at 785 nm (τfl = 1.50 ns). In contrast, upon photoexcitation between 350 and 450 nm, the dyad also exhibits a photoinduced electron transfer from the {[Ru(phen)3]2+} moiety to PDI-Py, generating the charge-separated intermediate state {Ru(III)-(PDI-Py)•-} (4 μs). This state subsequently decays to the long-lived triplet excited state 3PDI-Py (36 μs), which is able to sensitize singlet oxygen (1O2). Overall, tuning 1O2 photoactivation or NIR fluorescence makes RuPDI-Py a promising candidate for using absorbed light energy to perform the desired functions in theranostic applications.

Coordination of a triazine ligand with CuII and AgI investigated by spectral, structural, theoretical and docking studies

Two complexes of 5-phenyl-3-(pyridin-2-yl)-1,2,4-triazine (PPTA), namely (ethanol-κO)bis(nitrato-κO)[5-phenyl-3-(pyridin-2-yl-κN)-1,2,4-triazine-κN²]copper(II), [Cu(NO₃)₂(C₁₄H₁₀N₄)(C₂H₆O)] or [Cu(NO₃)₂(PPTA)(EtOH)] (1), and bis[μ-5-phenyl-3-(pyridin-2-yl)-1,2,4-triazine]-κ³N¹:N²,N³;κ³N²,N³:N¹-bis[(nitrato-κO)silver(I)], [Ag₂(NO₃)₂(C₁₄H₁₀N₄)₂] or [Ag₂(NO₃)₂(μ-PPTA)₂] (2), were prepared and characterized by elemental analysis, FT-IR spectroscopy and single-crystal X-ray diffraction. The X-ray structure analysis of 1 revealed a copper complex with square-pyramdial geometry containing two O-donor nitrate ligands along with an N,N'-donor PPTA ligand and one O-donor ethanol ligand. In the binuclear structure of 2, formed by the bridging of two PPTA ligands, each Ag atom has an AgN₃O environment and square-planar geometry. In addition to the four dative interactions, each Ag atom interacts with two O atoms of two nitrate ligands on adjacent complexes to complete a pseudo-octahedral geometry. Density functional theory (DFT) calculations revealed that the geometry around the Cu and Ag atoms in 1^opt and 2^opt (opt is optimized) for an isolated molecule is the same as the experimental results. In 1, O-H...O hydrogen bonds form R₁²(4) motifs. In the crystal network of the complexes, in addition to the hydrogen bonds, there are π-π stacking interactions between the aromatic rings (phenyl, pyridine and triazine) of the ligands on adjacent complexes. The ability of the ligand and complexes 1 and 2 to interact with ten selected biomacromolecules (BRAF kinase, CatB, DNA gyrase, HDAC7, rHA, RNR, TrxR, TS, Top II and B-DNA) was investigated by docking studies. The results show that the studied compounds can interact with proteins better than doxorubicin (except for TrxR and Top II).

The effect of incorporating carboxylic acid functionalities into 2,2′-bipyridine on the biological activity of the complexes formed: synthesis, structure, DNA/protein interaction, antioxidant activity and cytotoxicity

Incorporation of carboxylic acid group in the bipyridine moiety has resulted in showing differences in DNA/protein binding affinity, efficiency in antioxidant activity and cytotoxicity.

Modular Approaches to Diversified Soft Lewis Basic Complexants through Suzuki-Miyaura Cross-Coupling of Bromoheteroarenes with Organotrifluoroborates

Remediation or transmutation of spent nuclear fuel obtained as a function of energy production and legacy waste remains a significant environmental concern. Substantive efforts over the last three decades have focused on the potential of soft-Lewis basic complexants for the chemoselective separation of trivalent actinides from lanthanides in biphasic solvent systems. Recent efforts in this laboratory have focused on the concept of modularity to rapidly prepare complexants and complexant scaffolds not easily accessible via traditional linear methods in a convergent manner to better understand solubility and complexation structure/activity function in process-relevant solvents. The current work describes an efficient method for the construction of diversified complexants through multi-Suzuki-Miyaura cross-coupling of bromoheteroarenes with organotrifluoroborates affording efficient access to 22 novel materials in 43-99% yield over two, three, or four cross-couplings on the same scaffold. Optimization of the catalyst/ligand system, application, and limitations are reported herein.

Pd-Catalyzed Diamination of 1,2,4-Triazinyl Complexant Scaffolds

As part of ongoing efforts in this laboratory to design and synthesize multidentate soft-N-donors as effective complexants for chemoselective minor actinide extraction from used nuclear fuel, a series of aminated mono-1,2,4-triazinylpyridines were required. This study focuses on streamlining convergent access to a diverse array of functionalized N-donors using Pd-catalysis from a common synthon affording access to pyridinyl triazines as the 4,4'-amino derivatives which are commercially limited and unsuccessful in traditional condensation chemistry. A general Pd-catalyzed method for the double amination of functionalized pyridinyl-1,2,4-triazines with low catalyst/ligand loadings enabling the formation of 16 novel complexants is presented.

DNA interaction and photocleavage properties of Ru (II) complexes [Ru(bpy)₂(pibi)]²⁺ and [Ru(phen)₂(pibi)]²⁺

A new asymmetry ligand pibi (pibi = 2-(pyridine-2-yl)-1-H-imidazo[4,5-f]benzo[d]imidazolone) and its ruthenium complexes with [Ru(L)2(pibi)](2+) (L = bpy (2, 2'-bipyridine), phen (1, 10-phenanthroline)), have been synthesized and characterized. The binding of two complexes with calf thymus DNA has been investigated by spectroscopic and viscosity measurement. The results indicate that both complexes can bind to CT-DNA through intercalative mode. Under irradiation at 365 nm, both complexes can partly promote the photocleavage of plasmid pBR322DNA. The low singlet oxygen generation abilities of the two complexes may be the factor for the low DNA photocleavage abilities.

DNA-binding and photocleavage studies of ruthenium(II) complexes containing asymmetric intercalative ligand

A novel asymmetric ligand 2-(pyridine-2-yl)-1-H-imidazo[4,5-i]dibenzo[2,3-a:2',3'-c]phenazine (pidbp) and its ruthenium complexes [Ru(L)(2)(pidbp)](2+) (L=bpy (2, 2'- bipyridine), phen (1, 10 - phenanthroline)), have been synthesized and characterized by elemental analysis, ES-MS, (1)H NMR. Various methods support the conclusion that both Ru(II) complexes can intercalate into DNA base pairs. Complex [Ru(bpy)(2)(pidbp)](2+)4 exhibits its DNA "molecular light switch" properties. Furthermore, the two complexes are efficient DNA-photocleavers under irradiation at 365 nm, and complex 5 exhibits a stronger DNA-photocleavage efficiency than complex 4. The mechanism of DNA cleavage is an oxidative process by generating singlet oxygen.