New Chlorido(dimethyl sulfoxide)iridium(III) Complexes with N6-Substituted Adenines - Kinetic N(7) versus Thermodynamic N(9) Coordinated Adenine Isomers

The Role of Fluorine-Substituted Positions on the Phase Transition in Organic-Inorganic Hybrid Perovskite Compounds

Although research on organic-inorganic hybrid perovskites (OIHPs) has grown exponentially in the past two decades, the high phase transition temperature of OIHP materials is still one of the insurmountable difficulties. Herein, a series of A₂BX₄ type OIHP materials [(2,n-DFBA)₂PbCl₄] (n = 3, for 1; n = 4, for 2; n = 5, for 3; n = 6, for 4) have been prepared by reactions of double-substituted difluorobenzylamine (difluorobenzylamine = DFBA) with lead chloride in concentrated HCl aqueous solution. It was found the OIHP compounds 1-3 proceed a switchable phase transition with phase transition temperatures (T_c) at 449 K (1), 462 K (2) and 500 K (3), higher than that of the parent compound [(BA)₂PbCl₄] (BA = benzylammonium) at 438 K, but compound 4 exhibits no phase transition. A crystal structure analysis elucidated that the organic template ligands DFBA lead in the inorganic part in compounds 1-3 to a two-dimensional (2D) perovskite structure, while that in compound 4 leads to a one-dimensional (1D) chain structure. The different double-substituted positions of fluorine atoms on benzylamine have important influences on the phase transition in compounds 1-4.

Iridium(III) coordination of N(6) modified adenine derivatives with aminoacid chains

In this manuscript we report the preparation of three N⁶-aminoacid-adenine-derivatives: N-(7H-purin-6-yl)glycine·0.5H₂O (N⁶-GlyAde), N-(7H-purin-6-yl)-β-alanine·1.5H₂O (N⁶-β-AlaAde) and N-(7H-purin-6-yl)-γ-aminobutyric·2H₂O (N⁶-GabaAde) and the synthesis and X-ray characterization of three Ir(III) NAMI-A derivatives (NAMI-A is [imidazoleH][trans-Ru^IIICl₄(DMSO-κS)(imidazole)]) [trans-Ir^IIICl₄(DMSO-κS)(N³-H)-(7H-purin-6-yl)glycine-κN⁹] (1), [trans-Ir^IIICl₄(DMSO-κS)(N³-H)-(7H-purin-6-yl)-β-alanine-κN⁹] hydrate (2) and [trans-Ir^IIICl₄(DMSO-κS)(N³-H)-(7H-purin-6-yl)-γ-aminobutyryl-κN⁹] (3). In all complexes the metal center shows octahedral geometry with coordination to four chlorido ligands and one S coordinated dimethylsulfoxide (DMSO-κS). The coordination sphere of the metal is completed by the modified adenine molecule which is bound via N(9) and protonated at N(3). In two complexes the importance of lone pair (lp)-π interactions involving the adenine ring have been studied using density functional theory (DFT) calculations and the Bader's theory of atoms in molecules. Furthermore, the ability of complexes (1-3) to affect the cell viability was evaluated against three different cancer cell lines: human lung carcinoma cells (A549), human cervical carcinoma cells (HeLa) and human breast cancer cells (MCF7). We have also analyzed their ability to cleave the DNA experimentally and their affinity for two models of DNA has been studied using molecular docking simulations.

Ir(2-phenylpyridine)2(benzene-1,2-dithiolate) anion as a diastereoselective metalloligand and nucleophile: stereoelectronic effect, spectroscopy, and computational study of the methylated and aurated complexes and their oxygenation products

The anionic complex [Ir(2-phenylpyridine)2(benzene-1,2-dithiolate)](-) ([IrSS](-)) is a nucleophile and metalloligand that reacts with methyl iodide and AuPR3(+) (R = Ph or Et) to form S-methylated complexes (thiother-thiolate and dithiother complexes) and S-aurated complexes, respectively. The reactions are completely diastereselective, producing only the enantiomers ΛS and ΔR or ΛSS and ΔRR. The diastereoselectivity is stereoelectronically controlled by the orientation of the highest occupied molecular orbital (HOMO) of [IrSS](-) arising from filled dπ-pπ antibonding interactions, and the chirality of the iridium ion. Methylation or auration removes the high-energy lone pair of the thiolate S atom, leading to low-lying HOMOs composed mainly of the Ir d-orbital and the 2-phenylpyridine π (ppyπ) orbital. The methylated and aurated complexes can be oxidized by H2O2 or peracid to give sulfinate-thiother, disulfoxide, and sulfinate-sulfoxide complexes, and the oxygenation further stabilizes the HOMO. All the complexes are luminescent, and their electronic spectra are interpreted with the aid of time-dependent density functional theory calculations. The thiother-thiolate complex exhibits ligand(S)-to-ligand(π* of ppy)-charge-transfer/metal-to-ligand-charge-transfer absorption (LLCT/MLCT) and a relatively low-energy (3)LLCT/MLCT emission, while the other complexes display (3)ππ*/MLCT emissions.

7-Methylguanine: protonation, formation of linkage isomers with trans-(NH3)2Pt(II), and base pairing properties

Three protonated forms of 7-methylguanine (7-MeGH, 1) with different counter ions, [7-MeGH(2)]X (X = NO(3), 1a; ClO(4), 1b; BF(4), 1c) and two Pt(II) complexes, trans-[Pt(NH(3))(2)(7-MeGH-N9)(2)](ClO(4))(2) (4) and trans-[Pt(NH(3))(2)(7-MeGH-N9)(7-MeGH-N3)](ClO(4))(2)·3H(2)O (5) are described and their X-ray crystal structures are reported. 1a-1c form infinite ribbons via pairs of intermolecular hydrogen bonds between N1H···O6 and N3···N2H(2) sites, with anions connecting individual ribbons, thereby generating extended sheets. 4 and 5 do not display unusual features, except that 5 represents a rare case of a bis(nucleobase) complex of Pt(II) in which linkage isomers occur. Unlike in a previously reported compound, [Pt(dien)(7-MeGH-N9)](NO(3))(ClO(4)), the Pt coordination planes and the 7-MeGH planes are not coplanar in 4 and 5. The hydrogen bonding behaviour of 7-MeGH, free and when platinated at N9 (complex 4), was studied in Me(2)SO-d(6). It revealed the following: (i) there is no detectable self-association of 1 in Me(2)SO solution. (ii) 1 and 1-methylcytosine (1-MeC) form Watson-Crick pairs. (iii) 4 does not self-associate. (iv) 4 associates with 1-MeC in the Watson-Crick fashion. (v) 4 and 1 interact in solution, but no model can be proposed at present. (vi) Remarkable interaction shifts between 4 and 1 occur when NH(3) is liberated from trans-(NH(3))(2)Pt(II) to give NH(4)(+) in Me(2)SO-d(6). Feasible models, which imply the presence of deprotonated 7-MeG(-) species are proposed. Finally, DFT calculations were carried out to qualitatively estimate the effect of 7-MeGH acidity in [Pt(dien)(7-MeGH-N9)](2+) in dependence of the dihedral angle between the Pt coordination plane and the nucleobase.