Luminescence of mononuclear Pt(ii) complexes with glycolate: external stimuli-induced excimer emission changes to oligomer emissions

In vitro cytotoxicity of Mn(I) and Ru(II) carbonyls with a diphenyl pyridyl phosphine coligand towards leukaemia

Human acute monocytic leukaemia cells were tested under both dark and light conditions for their susceptibility to Mn(I) and Ru(II) carbonyl complexes with a diphenyl pyridyl phosphine coligand. The Ru(II) complex (IC₅₀ = 7.13 ± 0.8 μM) displayed higher outstanding potency against leukaemia than the Mn(I) analogue (54.58 ± 4.1 μM) in the dark and both complexes were completely harmless to healthy mouse bone marrow cells.

Cyclometalated Platinum(II) Complexes in a Cis-N,N Configuration: Photophysical Properties and Isomerization to Trans Isomers

Synthesis, isomerization, and photophysical properties of novel cis-N,N-cyclometalated complexes [Pt(C^∧N)(l-Phe)] (C^∧N = benzoquinolinate (1), phenylpyridinate (2), 2-(p-tolyl)pyridinate (3), and 1-phenylpyrazolate (4); l-Phe^- = l-phenylalaninate) are reported herein. In solution, the cis forms of the complexes isomerize to their trans forms via an associative mechanism. This cis/trans isomerism barely influences the absorption and luminescence properties of the complexes in solution, except for a characteristic absorption at approximately 340 nm in the absorption spectra of the cis complexes that is not observed for the trans complexes. Interestingly, the cis complexes are spontaneously assembled in a crystalline phase and show bathochromic absorption and emission colors compared with those of the corresponding trans isomers, which are aggregated in an amorphous phase. cis-1 and cis-2 demonstrate hypsochromic luminescence mechanochromism. The influence of the geometrical isomerism on the photophysical properties and the isomerization mechanism are supported by density functional theory calculations.

Light-activated cytotoxicity of dicarbonyl Ru(II) complexes with a benzimidazole coligand towards breast cancer

Reaction between [RuCl₂(CO)₂]_n and 1H-benzimidazol-2-ylmethyl-(N-phenyl)amine ligands (L^R) functionalized with various electron-donating and electron-withdrawing substituents on the phenyl ring (R = H, 4-CH₃, 4-Cl, 4-COOCH₃, and 3-COOCH₃) afforded the dark-stable photoactivatable carbon monoxide prodrugs of the general formula [RuCl₂(CO)₂L^R]. Release of the CO molecules from the Ru(II) compounds was examined by monitoring the electronic and IR spectra upon illumination at 365 nm. A noticeable decrease in the intensities of the two characteristic ν(CO) modes for Ru(CO)II2 species, and the growth of two new bands for the mono-carbonyl species and free CO, were the main features of the photolysis profiles. The cytotoxicity of the complexes towards breast cancer (MCF-7) cells was assessed with and without illumination at 365 nm. All the complexes except that with a 4-COOCH₃ group (IC₅₀ = 45.08 ± 3.5 μM) are nontoxic under dark conditions. Upon illumination, all the compounds acquired cytotoxicity in the following order: H > 4-COOCH₃ > 4-CH₃ > 4-Cl > 3-COOCH₃. Investigation of the cytotoxicity of the CO-depleted fragments showed that the light-induced cytotoxicity can be attributed to the liberated CO and CO-depleted metal fragments, including the liberated benzimidazole ligands.

Phototriggered cytotoxic properties of tricarbonyl manganese(I) complexes bearing α-diimine ligands towards HepG2

Reaction between bromo tricarbonyl manganese(I) and N,N'-bis(phenyl)-1,4-diaza-1,3-butadiene ligands, bearing different electron-donating and electron-withdrawing groups R = OCH₃, Cl, and NO₂ in the ortho- and para-positions on the phenyl substituent, afforded [MnBr(CO)₃(N-N)] complexes. The influence of the character and position of the substituent on the dark stability and carbon monoxide releasing kinetics was systematically investigated and correlated with the data of the time-dependent density functional theory calculations. The combined UV/Vis and IR data clearly revealed that the aerated solutions of [MnBr(CO)₃(N-N)] in either coordinating or noncoordinating solvents are dark stable and the fluctuations observed during the incubation period especially in the case of the nitro derivatives may be attributed to the exchange of the axial bromo ligand with the coordinating solvent molecules. The free ligands and nitro complexes were non-cytotoxic to HepG2 cells under both the dark and illumination conditions. In the dark, Mn(I) compounds, incorporating o-OCH₃ and o-Cl, exhibited excellent cytotoxicity with IC₅₀ values of 18.1 and 11.8 μM, while their para-substituted analogues were inactive in the dark and active upon the irradiation at 365 nm with IC₅₀ values of 5.7 and 6.7 μM, respectively.

Modulation of Metallophilic and π-π Interactions in Platinum Cyclometalated Luminophores with Halogen Bonding

Luminescent cyclometalated complexes [M(C^N^N)CN] (M=Pt, Pd; HC^N^N=pyridinyl- (M=Pt 1, Pd 5), benzyltriazolyl- (M=Pt 2), indazolyl- (M=Pt 3, Pd 6), pyrazolyl-phenylpyridine (M=Pt 4)) decorated with cyanide ligand, have been explored as nucleophilic building blocks for the construction of halogen-bonded (XB) adducts using IC₆ F₅ as an XB donor. The negative electrostatic potential of the CN group afforded CN⋅⋅⋅I noncovalent interactions for platinum complexes 1-3; the energies of XB contacts are comparable to those of metallophilic bonding according to QTAIM analysis. Embedding the chromophore units into XB adducts 1-3⋅⋅⋅IC₆ F₅ has little effect on the charge distribution, but strongly affects Pt⋅⋅⋅Pt bonding and π-stacking, which lead to excited states of MMLCT (metal-metal-to-ligand charge transfer) origin. The energies of these states and the photoemissive properties of the crystalline materials are primarily determined by the degree of aggregation of the luminophores via metal-metal interactions. The adduct formation depends on the nature of the metal and the structure of the metalated ligand, the variation of which can yield dynamic XB-supported systems, exemplified by thermally regulated transition 3↔3⋅⋅⋅IC₆ F₅ .

Cytotoxicity of photoactivatable bromo tricarbonyl manganese(i) compounds against human liver carcinoma cells

Two series of photoinduced tricarbonyl manganese(i) compounds were prepared from the reaction of [MnBr(CO)3(2-C(H)[double bond, length as m-dash]O)] (2-C(H)[double bond, length as m-dash]O: quinoline-2-carboxaldehyde and pyridine-2-carboxaldehyde) and para-substituted aniline derivatives (X = OH, OCH3, Cl and NO2). Different electron-donating and electron-withdrawing substituents were introduced in the para-position of the phenyl ring to investigate their influence on the stability of the compounds in the dark and the photophysical properties upon illumination at 525 nm. When kept in the dark, the aerated solutions of the complexes in dimethyl sulfoxide (DMSO) and CH2Cl2 were stable. In the solution, the complexes bearing electron-withdrawing substituents, exchange their bromo ligands with DMSO solvent molecules, as evidenced from infrared and UV/Vis studies as well as time-dependent density functional theory (TDDFT) calculations. The complexes were assessed for their cytotoxicity, both in the dark and upon exposure to a 525 nm LED, against the human hepatocarcinoma cell line (HepG2). A marked reduction in the viability of HepG2 cells treated with the complex functionalized with quinoline and methoxy substituent was observed after illumination in a dose-dependent manner, with an IC50 value of 7.1 μM, making it the most phototoxic compound in our study.

AIPE-active Pt(ii) complexes with a tunable triplet excited state: design, mechanochromism and application in anti-counterfeiting

A series of AIPE-active Pt(ii) complexes exhibit tunable triplet excited state properties, mechanochromic behavior and potential application in anti-counterfeiting.