[Cu6(NGuaS)6]2+ and its oxidized and reduced derivatives: Confining electrons on a torus

The hexanuclear thioguanidine mixed‐valent copper complex cation [Cu₆(NGuaS)₆]⁺² (NGuaS = o‐SC₆H₄NC(NMe₂)₂) and its oxidized/reduced states are theoretically analyzed by means of density functional theory (DFT) (TPSSh + D3BJ/def2‐TZV (p)). A detailed bonding analysis using overlap populations is performed. We find that a delocalized Cu‐based ring orbital serves as an acceptor for donated S p electrons. The formed fully delocalized orbitals give rise to a confined electron cloud within the Cu₆S₆ cage which becomes larger on reduction. The resulting strong electrostatic repulsion might prevent the fully reduced state. Experimental UV/Vis spectra are explained using time‐dependent density functional theory (TD‐DFT) and analyzed with a natural transition orbital analysis. The spectra are dominated by MLCTs within the Cu₆S₆ core over a wide range but LMCTs are also found. The experimental redshift of the reduced low energy absorption band can be explained by the clustering of the frontier orbitals. © 2017 Wiley Periodicals, Inc.     

DFT/TD‐DFT investigation on Ir(III) complexes with N‐heterocyclic carbene ligands: Geometries,electronic structures,absorption, and phosphorescence properties

Iridium(III) complexes with N‐heterocyclic (NHC) ligands including fac‐Ir(pmb)₃ (1), mer‐Ir(pmb)₃ (2), (pmb)₂Ir(acac) (3), mer‐Ir(pypi)₃ (4), and fac‐Ir(pypi)₃ (5) [pmb = 1‐phenyl‐3H‐benzimidazolin‐2‐ylidene, acac = acetoylacetonate, pypi = 1‐phenyl‐5H‐benzimidazolin‐2‐ylidene; fac = facial, mer = meridional] were investigated theoretically. The geometry structures of 1–5 in the ground and excited state were optimized with restricted and unrestricted DFT (density functional theory) methods, respectively (LANL2DZ for Ir atom and 6‐31G for other atoms). The HOMOs (highest occupied molecular orbitals) of 1–3 are composed of d(Ir) and π(phenyl), while those of 4 and 5 are contributed by d(Ir) and π(carbene). The LUMOs (lowest unoccupied molecular orbitals) of 1, 2, 4, and 5 are localized on carbene, but that of 3 is localized on acac. The calculated lowest‐lying absorptions with TD‐DFT method based on Perdew‐Burke‐Erzenrhof (PBE) functional of 1 (310 nm), 2 (332 nm), and 3 (347 nm) have ML_carbeneCT/IL_{phenyl→carbene}CT (MLCT = metal‐to‐ligand charge transfer; ILCT = intraligand charge transfer) transition characters, whereas those of 4 (385 nm) and 5 (389 nm) are assigned to ML_carbeneCT/IL_{carbene→carbene}CT transitions. The phosphorescences calculated by TD‐DFT method with PBE0 functional of 1 (386 nm) and 2 (388 nm) originate from ³ML_carbeneCT/³IL_{phenyl→carbene}CT excited states, but those of 4 (575 nm) and 5 (578 nm) come from ³ML_carbeneCT/³IL_{carbene→carbene}CT excited states. The calculated results showed that the carbene and phenyl groups act as two independent chromophores in transition processes. Compared with 1 and 2, the absorptions of 4 and 5 are red‐shifted by increasing the effective π‐conjugation groups near the C_carbene atom. We predicated that (pmb)₂Ir(acac) is nonemissive, because the LUMO of 3 is contributed by the nonemissive acac ligand. © 2009 Wiley Periodicals, Inc. J Comput Chem, 2010     

Structural studies and quantum chemical calculations of Cr(III), Fe(III) and Ru(III) bromazepam complexes

The reaction of bromazepam (7‐bromo‐1,3‐dihydro‐5‐(2‐pyridyl)‐2H ‐1,4‐benzodiazepin‐2‐one, BZM) with Cr(III) ( 1 ), Fe(III) ( 2 ) and Ru(III) ( 3 ) salts gives complexes of the type [M(BZM)₃]⋅3X (X = Cl or NO₃). Structural characterization was extensively carried out using various analytical and spectral tools such as infrared, ¹H NMR and UV–visible spectroscopies and magnetic, conductance, elemental and thermal analyses. BZM is a bidentate ligand and interacts with the metal ions via the pyridine and benzodiazepin‐2‐one nitrogen atoms. The magnetic and electronic properties of 2 and 3 are consistent with low‐spin octahedral complexes. The three BZM molecules are non‐isoenergetically coordinated to the metal ions and this is reflected in the values of the second‐order interaction energy. The antibacterial activity was studied using Staphylococcus aureus and Escherichia coli . Coordination of BZM to Cr(III) or Ru(III) ions leads to a marked increase in toxicity with respect to the inactive Fe(III) complex 2 .     

Cu2(μ-dppb)2(μ-Cl)2的合成、晶体结构及非线性光学性质

The complex Cu₂(μ-dppb)₂(μ-Cl)₂ has been synthesized from the reaction of CuCl， dppb and (n-Bu)₄NCl. The crystal belongs to the triclinic with space group P1. The unit cell parameters are: a=9.939(4)?， b=10.083(6)?， c=14.104(5)?， α=76.46(3)°， β=71.02(2)°， γ=70.87(5)°. The single crystal X-ray diffraction analysis reveals that it has a bi-ring structure with a symmetry center at the middle of two Copper atoms. The outer ring is a 14-membered ring of Cu-dppb-Cu-dppb， and the inner ring is a 4-membered ring composed of two Cl^- and two Cu(Ⅰ). Investigation of third-order optical nonlinearity shows that it exhibits considerable nonlinear absorptive and self-defocusing effect with α₂=1.75×10^-13m·W^-1 and n₂=3.19×10^-18m²·W^-1. CCDC: 193113.     

A New Preparative Route of the “Stepped‐Cubane” Tetranuclear Copper(II) Compound, [Cu4(μ2‐OH)2(μ3‐OH)2Cl2(bipy)4]Cl2 · 6H2O

The compound [Cu₄(μ₂‐OH)₂(μ₃‐OH)₂Cl₂(bipy)₄]Cl₂ · 6H₂O ( 1 ) was obtained by recrystallization of [Cu(HB)₂(2, 2′‐bipy)] · H₂O (H₂B = diphenylglycolic acid) from EtOH/CH₂Cl₂ and their structure has been determined by single‐crystal X‐ray analysis. The cationic complex may be described as based on a Cu₄(OH)₄ core with a “stepped cubane” structure. The coordination polyhedron around each copper is a distorted square pyramid. The tetranuclear units are linked in the crystal by C‐H…Cl hydrogen bonds and by π‐π interactions between bipyridine rings. IR data are also presented.     

Insights into the luminescent properties of anionic cyclometalated iridium(III) complexes with ligands derived from natural products

In the search of remarkable anionic electroluminescent semiconductors to be applied in energy conversion devices such as Light Emitting Electrochemical Cells, we report the electronic, photophysical, and charge injection/transfer properties of a series of cyclometalated iridium(III) complexes through a DFT/TD‐DFT procedure. The proposed semiconductors involve bidentated ligands based on natural products (salicylic acid and boldine), and phenylpyridine and phenylpyrazole as the cyclometalating units. The proposed compounds emit in the range of 446 to 571 nm, where the boldine based compounds have red‐shifted emissions compared to their analogs with salicylic acid. Blue phosphors were obtained by the use of phenylpyrazole units; however, the ligand field is weak in these cases compared to the ligand field exerted by the phenylpyridine ligands. The latter allows the accessibility to the radiationless states for emitters below 495 nm as a result of the increased stability of the metal centered excited states; consequently, the luminescent quantum yield could be decreased. Conversely, the semiconductors with phenylpyridine units show a restricted accessibility to radiationless processes, which could result in emitters with a high luminescent quantum yield and low non‐radiative constants. Finally, the proposed anionic semiconductors show a better balance between hole/electron transfer rate compared to related cationic Ir(III) complexes; while, the easier hole‐electron injection is favored for semiconductors with salicylic acid and phenylpyridine units.     

Structure of Bischloro tris (1, 10‐phenanthroline) copper (II) Dichloromethane Solvate Nonahydrate: [Cu(phen)3]Cl2CH2Cl2·9H2O

The crystal and molecular structures of [Cu(phen)₃] Cl₂ · CH₂Cl₂^.9H₂O (PHEN= 1, 10‐pbenanthroline) have been determined by X‐ray crystallography. The complex crystallizes in triclinic system, space group P1, with lattice parameters a = 1.26000(3), b = 1.37525(4), c = 1.42750(3)nm, α = 85.2970(1),β = 66.8400(1), γ= 83.09(1)°, and Z = 2. The coordinated cations contain a six‐coordinated copper atom chelated by three PHEN ligands, and the Jahn‐Teller effect of the Cu(II) ion results in a distorted octahedral arrangement with the six Cu? N distances ranging from 0.2112(6) to 0.2265(7) nm. In addition to the copper coordinated cation, there are two chloride ions, one dichloromethane solvate and nine water molecules in its asymmetric unit. In the solid state, the title compound forms three dimensional network structures through hydrogen bonds. The intermolecular hydrogen bonds connect the [Cu(phen)₃]²⁺, chloride ion, dichloromethane solvate and H₂O moieties altogether.     

Self-assembly of the octanuclear cluster [Cu8(OH)10(NH2(CH2)2CH3)12]6+ and the one-dimensional N-propylcarbamate-linked coordination polymer {[Cu(O2CNH(CH2)2CH3)(NH2(CH2)2CH3)3](ClO4)}n

The reaction of Cu(ClO4)2.6-H2O and n-propylamine in methanol gives two high-nuclearity products of well-defined compositions. At amine concentrations greater than seven equivalents compared to copper ion concentration, the system fixes carbon dioxide from air to form the one-dimensional carbamate-bridged coordination polymer, {[Cu(mu2-O,O'-O2CNH(CH2)2CH3)(NH2(CH2)2CH3)3](ClO4)}n ({1-ClO4}n). Lower relative amine concentrations lead to the self-assembly of an octanuclear copper-amine-hydroxide cluster [Cu8(OH)10(NH2(CH2)2CH3)12]6+ (2). Both compounds exhibit unique structures: {1-ClO4}n is the first mu2-O,O'-mono-N-alkylcarbamate-linked coordination polymer and 2 is the largest copper-hydroxide-monodentate amine cluster identified to date. The crystal structures indicate that the size of the n-propyl group is probably crucial for directing the formation of these compounds. Magnetic susceptibility studies indicate very weak antiferromagnetic coupling for 1. The octanuclear cluster 2 displays slightly stronger net antiferromagnetic coupling, despite the presence of a number of Cu-O(H)-Cu angles below the value of about 97 degrees that would normally be expected to yield ferromagnetic coupling.     

Preparation and characterization of copper sulfide nanoparticles from symmetrical [(Bu)2NC(S)NC(O)C6H3(3,5-NO2)2]2Cu(II) and [(Bu)2NC(S)NC(O)C6H4(4-NO2)]2Cu(II) complexes by thermolysis

Trigonal copper sulfide nanoparticles were synthesized from symmetrical [(Bu)₂NC(S)NC(O)C₆H₃(3,5-NO₂)₂]₂Cu(II) and [(Bu)₂NC(S)NC(O)C₆H₄(4-NO₂)]₂Cu(II) complexes by thermolysis in the presence of surfactant oleylamine. The symmetrical copper complexes were synthesized by reaction of copper(II) acetate with N-(3,5-dinitrobenzoyl)-N′,N′-dibutylthiourea and N-(4-nitrobenzoyl)-N′,N′-dibutylthiourea. The symmetrical copper complexes were characterized by FT-IR spectroscopy, elemental analysis, and mass spectrometry (MS-APCI). The single-crystal X-ray structure of [(Bu)₂NC(S)NC(O)C₆H₄(4-NO₂)]₂Cu(II) has been determined from single-crystal X-ray diffraction data. These metal complexes have been used as single source precursors for the preparation of copper sulfide nanoparticles. The deposited copper sulfide nanoparticles were characterized by X-ray powder diffraction and transmission electron microscopy.     

Theoretical investigation on the spectroscopic properties of cyclometallated iridium (III) complexes and the deprotonation influence on them in solution

Electronic structures and spectroscopic properties of mixed‐ligand cyclometallated iridium complexes with general formula [Ir(N?C)₂(N?N)]⁺ (N?C = 2‐phenylpyridine, N?N = Hcmbpy = 4‐carboxyl‐4^′‐methyl‐2,2^′‐bipyridine, 1 ; H₂dcbpy = 4,4^′‐dicarboxyl‐2,2^′‐bipyridine, 2 ) were studied theoretically. The geometries of the complexes in ground and excited state were optimized at B3LYP and CIS levels, respectively. The absorption and emission of the complexes in CH₃CN solutions were calculated by time‐dependent density functional theory (TD‐DFT) with the PCM solvent model. The calculated absorptions and emissions of the complexes are in good agreement with the measured results. The deprotonation influence on the electronic structure and the optical properties of 2 was also investigated. The results indicate that the deprotonation which occurs on the COOH groups influences the geometries of the complexes in ground and excited state slightly but leads to significant blue‐shifts in low energy absorption and emission maximum. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2010     

Electrochemical Study of Tryptophan‐containing Peptides‐Cu(II) Complexes

This article presents rotating ring‐disc electrode investigations of (A = alanine, F = phenylalanine, G = glycine, L = leucine, W = tryptophan) W, GW, WGG, GWG, GGW, GWGG, and GGWA. In addition, the analyses of the copper complexes of the same peptides plus GF, FGG, GFG, FGG, GGFL, GGGG, AAAA, and GGGGGG have been carried out. The results suggest that an influential step in the reaction mechanism of the copper complexes of the tryptophan‐containing peptides (W‐peptides) is the alteration of the peptide structure after the one‐electron oxidation of tryptophan. This change in structure leads to a positive shift in redox potential for the Cu(III)/Cu(II) couple. The analytical implications for the electrochemical detection of W‐peptides as their copper complexes are applied for detection of W‐containing bioactive peptides. Application of the optimized detection conditions of peptides as their Cu(II) complexes are as follows: (1) If sensitivity is paramount, detect the copper complexes at a relatively high potential, around 0.7 V vs. Ag/AgCl. (2) If selectivity is paramount, use a dual electrode detector, oxidize at an upstream anode at 0.4 V, and detect at the downstream cathode at 0–0.1 V.     

两个单核镉、锌配合物M（2－SC_5H_3NH－3－SiMe_3）_2Cl_2（M＝Cd，Zn）的合成与晶体结构

以大空阻的３．三甲基硅－吡啶－２－硫酚为配体，合成了２个单核镉、锌配合物，并用Ｘ射线单晶衍射法测定了其晶体结构．