Nm For Complexes Research Articles

The effect of halides on Cd(II)-based metal coordination complexes with indazole and benzimidazole skeletons: Crystal structure, Hirshfeld surface analysis and properties

A set of Cd(II)-based metal coordination complexes with indazole and benzimidazole scaffolds, namely, [Cd(IZBI)Cl2]n·H2O (1) [Cd(IZBI)Br2]n·H2O (2) [Cd(IZBI)I2]·H2O (3) (IZBI stands for 3-(1H-benzimidazol-2-yl)-1H-indazole), were obtained through solvothermal reaction conditions. They have been structurally characterized by elemental analysis, single-crystal X-ray diffraction and IR spectra. Single-crystal X-ray diffraction analysis reveals that complexes 1–3 show one-dimensional polymeric, dimeric and mono-nucleic features, respectively, which indicates that the halide anions affect the final structure of metal coordination complexes. The luminescent maximal peaks can be observed 448, 456 and 462 nm for complexes 1–3, respectively. Compared with the emission peak of IZBI, there exist bathochromic phenomena for metal coordination complexes 1–3, where the red-shifted values can be observed to be 46, 54 and 60 nm, respectively. The order of the photoluminescent emission peaks is summarized as the following: 3 > 2 > 1. The single-crystal X-ray diffraction analysis shows that it occurs the order of the dihedral angles between the pyrazole and imidazole rings (3 < 2 < 1). The Hirshfeld analysis demonstrates that there is a positive correlation between the sequence of H∙∙∙C/C∙∙∙H intermolecular contacts and the dihedral angles formed between the pyrazole and imidazole rings, which is negative correlation with the positions of the luminescent maxima. Additionally, the thermostable behaviors of these complexes were inspected in detail.

Three pseudo-dimeric lead halide complexes containing derivatives of 8-hydroxyquinoline, Cl2QPbX (X = Br, I), (Cl2Q)4Pb2:Synthesis, crystal structures, and fluorescence spectroscopic properties

Three new complexes, namely (5,7-Dichloro-8-hydroxyquinoline)PbX (X=Br, I) (1, 2) and Pb2(5,7-Dichloro-8-hydroxyquinoline)4 (3), were synthesized through solvent evaporation at ambient temperature. The crystal structures and fluorescence emission properties of these complexes were systematically investigated. An analysis using single crystal X-ray diffraction revealed that complexes 1-3 form pseudo-dimeric structures through the interaction between lead and neighboring oxygen via secondary contacts. A comparison between the structures of complex 2 and [Pb(μ-Q)I]2, a complex of PbI2 with 8-hydroxyquinoline, showed that the coordination polyhedron changed from a triangular pyramid to a distorted tetrahedron. This change may be attributed to the site resistance effect of the chlorine substituents coordinated to the quinoline ring. Complex 3 has a layered structure formed through secondary contacts and intramolecular hydrogen bonding C-H⋯O and C-H⋯Cl among the lamellar molecules. The maximum emission peak at 489 nm, 505 nm, and 543 nm for complex 1-3 can be assigned to the ligand-to-metal charge transfer (LMCT). The maximum emission peaks were red-shifted by 22 nm, 38 nm, and 75 nm, respectively, compared to the ligand. The number of ligands increases the conformational rigidity of the structure and the electron density on lead atoms causing the molecular structure to change, the energy alters, and the fluorescence peaks to move in the long-wave direction.

DFT study of UV–vis-properties of thiophene-containing Cu(β-diketonato)2 – Application for DSSC

Experimental and theoretically calculated UV–vis properties of three Cu(β-diketonato)2 complexes are presented. The Cu(β-diketonato)2 contains β-diketones without (β-diketone = acetylacetone, (CH3)COCH2CO(CH3), complex (1)), with one (β-diketone = thenoyltrifluoroacetone, (CF3)COCH2CO(C4H3S), complex (2)) and with two thiophene (β-diketone = (CF3)COCH2CO(C4H2S) (C4H3S), complex (3)) groups. More thiophenes on the β-diketonato ligand of Cu(β-diketonato)2, lead to a red shift of the experimental absorbance maxima of the UV–vis of the complex, from 295 nm for complex (1), to 340 nm for complex (2) to 390 nm for complex (3). Theoretical time dependant density functional theory calculations indicate that both the two strongest absorbance peaks of the ultraviolet–visible spectrum of Cu(acetylacetonato)2 are mainly ligand-to-metal charge-transfer excitations. However, the absorbance maxima of the UV–vis of thiophene-containing Cu(β-diketonato)2 are mainly ligand-to-ligand charge-transfer excitations. Calculated properties such as light harvesting energy (LHE = 0.47, 0.94 and 0.99 for (1)–(3) respectively), driving force for electron injection (ΔGinject = 1.43, 0.76 and 0.63 for (1)–(3) respectively), and driving force of dye regeneration (ΔGregenerate = 1.85, 2.16 and 1.49 for (1)–(3) respectively), are favourable for (1)–(3) to be considered as dyes in DSSCs. However, some structural modifications are needed to prevent intramolecular charge recombination after excitation.

Preparation of Biocidal Nanocomposites in X-ray Irradiated Interpolyelectolyte Complexes of Polyacrylic Acid and Polyethylenimine with Ag-Ions.

Due to the presence of cationic units interpolyelectrolyte complexes (IPECs) can be used as a universal basis for preparation of biocidal coatings on different surfaces. Metallopolymer nanocomposites were successfully synthesized in irradiated solutions of polyacrylic acid (PAA) and polyethylenimine (PEI), and dispersions of non-stoichiometric IPECs of PAA–PEI containing silver ions. The data from turbidimetric titration and dynamic light scattering showed that pH 6 is the optimal value for obtaining IPECs. Metal polymer complexes based on IPEC with a PAA/PEI ratio equal to 3/1 and 1/3 were selected for synthesis of nanocomposites due to their aggregative stability. Studies using methods of UV–VIS spectroscopy and TEM have demonstrated that the size and spatial organization of silver nanoparticles depend on the composition of polymer systems. The average sizes of nanoparticles are 5 nm and 20 nm for complexes with a molar ratio of PAA/PEI units equal to 3/1 and 1/3, respectively. The synthesized nanocomposites were applied to the glass surface and exhibited high antibacterial activity against both gram-positive (Staphylococcus aureus) and gram-negative bacteria (Salmonella). It is shown that IPEC-Ag coatings demonstrate significantly more pronounced biocidal activity not only in comparison with macromolecular complexes of PAA–PEI, but also coatings of PEI and PEI based nanocomposites.

Heteroctanuclear Au4Ag4 Cluster Complexes of 4,5-Diethynylacridin-9-One with Luminescent Mechanochromism.

Two heteroctanuclear Au4Ag4 cluster complexes of 4,5-diethynylacridin-9-one (H2L) were prepared through the self-assembly reactions of [Au(tht)2](CF3SO3), Ag(tht)(CF3SO3), H2L and PPh3 or PPh2Py (2-(diphenylphosphino)pyridine). The Au4Ag4 cluster consists of a [Au4L4]4− and four [Ag(PPh3)]+ or [Ag(PPh2Py)]+ units with Au4L4 framework exhibiting a twisted paper clip structure. In CH2Cl2 solutions at ambient temperature, both compounds show ligand fluorescence at ca. 463 nm as well as phosphorescence at 650 nm for 1 and 630 nm for 2 resulting from admixture of 3IL (intraligand) of L ligand, 3LMCT (from L ligand to Au4Ag4) and 3MC (metal-cluster) triplet states. Crystals or crystalline powders manifest bright yellow-green phosphorescence with vibronic-structured emission bands at 530 (568sh) nm for complex 1 and 536 (576sh) nm for complex 2. Upon mechanical grinding, yellow-green emission in the crystalline state is dramatically converted to red luminescence centered at ca. 610 nm with a drastic redshift of the emission after crystal packing is destroyed.

The effect of halogenation of salicylaldehyde on the antiproliferative activities of {Δ/Λ-[Ru(bpy)2(X,Y-sal)]BF4} complexes.

Ru(II) polypyridyl complexes are widely used in biological fields, due to their physico-chemical and photophysical properties. In this paper, a series of new chiral Ru(II) polypyridyl complexes (1-5) with the general formula {Δ/Λ-[Ru(bpy)2(X,Y-sal)]BF4} (bpy = 2,2'-bipyridyl; X,Y-sal = 5-bromosalicylaldehyde (1), 3,5-dibromosalicylaldehyde (2), 5-chlorosalicylaldehyde (3), 3,5-dichlorosalicylaldehyde (4) and 3-bromo-5-chlorosalicylaldehy (5)) were synthesized and characterized by elemental analysis, FT-IR, and 1H/13C NMR spectroscopy. Also, the structures of complexes 1 and 5 were determined by X-ray crystallography; these results showed that the central Ru atom adopts a distorted octahedral coordination sphere with two bpy and one halogen-substituted salicylaldehyde. DFT and TD-DFT calculations have been performed to explain the excited states of these complexes. The singlet states with higher oscillator strength are correlated with the absorption signals and are mainly described as 1MLCT from the ruthenium centre to the bpy ligands. The lowest triplet states (T1) are described as 3MLCT from the ruthenium center to the salicylaldehyde ligand. The theoretical results are in good agreement with the observed unstructured band at around 520 nm for complexes 2, 4 and 5. Biological studies on human cancer cells revealed that dihalogenated ligands endow the Ru(II) complexes with enhanced cytotoxicity compared to monohalogenated ligands. In addition, as far as the type of halogen is concerned, bromine is the halogen that provides the highest cytotoxicity to the synthesized complexes. All complexes induce cell cycle arrest in G0/G1 and apoptosis, but only complexes bearing Br are able to provoke an increase in intracellular ROS levels and mitochondrial dysfunction.

Carbazole-modified thiazolo[3,2-c][1,3,5,2]oxadiazaborinines exhibiting aggregation-induced emission and mechanofluorochromism.

Two highly emissive carbazole-containing thiazole-fused oxadiazaborinines were designed and synthesized. These N,O-chelated organoboron dyes displayed large Stokes shifts and remarkable solvatofluorochromism in solutions, as well as good thermal stability and comparatively high photoluminescence quantum yields (up to 34%) in the solid state. The presence of a carbazole donor unit, linked with the oxadiazaborinine acceptor via a phenyl linker, restricted intramolecular rotation, leading to enhanced aggregation-induced emission properties of the compounds: in THF/water mixtures with a large water percentage, they demonstrated the formation of emissive nanoaggregates with an average size of 79 and 89 nm for complexes 2 and 3, respectively. The introduction of bulky tert-butyl groups attached to the carbazole moiety induced significant mechanofluorochromic properties of the compounds.

Synthesis and physical property studies of cyclometalated Pt(II) and Pd(II) complexes with tridentate ligands containing pyrazole and pyridine groups

Novel substituted tridentate ligands, which contains a series of pyrazole and pyridine groups as donors, and their cyclometalated complexes have been successfully synthesized. The ligands and complexes were completely characterized by a variety of techniques, such as 1H NMR, UV–Vis, FT-IR, mass spectrometry and elemental analysis. Meanwhile, the single crystal structures of ligand 7 and complex 11 were determined by X-ray crystallography. For ligand 7, due to the effect of delocalization, the C(6)-C(7) bond length in the pyrazole ring is 0.05 Å shorter than a normal C-C bond. After coordinating with the metal centre, the configuration was limited by the coordination sphere, so the bond lengths and bond angles of complex 11 are different from those of ligand 7. Through photoluminescence in acetonitrile solution at ambient temperature, two emission bands have been found between 500 and 600 nm for complexes 9 and 10. Moreover, there are several absorbing bands respectively located at 240 to 250 nm and 300 to 310 nm for ligands 7 and 8 (π(L) → π*(L) and n → π*(L)). A red-shift was observed in the UV spectra, on comparing the complexes with electron-donating and electron-withdrawing groups on the ligand, which is due to the electronic effect of the substituent. One absorbing band is also found at 375 to 425 nm for complexes 9 and 10, and this band is attributed to a MLCT (dπ(Pt) → π*(L)).

Synthesis, crystal structures, photophysical, electrochemical studies, DFT and TD-DFT calculations and Hirshfeld analysis of new 2,2′:6′,2′′-terpyridine ligands with pendant 4′-(trimethoxyphenyl) groups and their homoleptic ruthenium complexes

[Ru(L1)2](PF6)2 (1) and [Ru(L2)2](PF6)2 (2): X-ray structures, CH⋯F/O, OH⋯F/N, CH⋯O/π, π⋯π interactions, absorption and emission spectra, DFT/TD-DFT, Hirshfeld analysis.

Efficient and low-efficiency-roll-off near-infrared (NIR) polymer light-emitting diodes (PLEDs) based on an asymmetric binuclear iridium(III)-complex

Abstract Through the replacement of the β-diketonate Hbtfa (Hbtfa=4,4,4-trifluoro-3-hydroxy-1-phenylbutanone) with the bis-β-diketonate ligand H2btp (H2btp=1,3-bis(4,4,4-trifluoro-1,3-dioxobutyl)benzene), structure converts from mononuclear [Ir(iqbt)2(btfa)] (1) (Hiqbt=1-(benzo[b]-thiophen-2-yl)-isoquinoline) to asymmetric dinuclear [(iqbt)2Ir-(btp)-Ir(iqbt)2] (2) framework toward larger molecule conjugation. Upon a significant bathochromic shift into the restrictive near-infrared (NIR) regime (λem=722 nm for complex 2 and 698 nm for complex 1), the superior phosphorescence (Φem=0.15 and τ = 1.27 μs) of complex 2 to that (Φem=0.08 and τ = 0.78 μs) of complex 1 is also approached. Moreover, within the realization of their solution-processed NIR polymer light-emitting diodes (NIR-PLEDs-I-II), complex-2-doped NIR-PLED-II in the presence of TmPyPB-assisted (TmPyPB=1,3,5-tri[(3-pyridyl)-phen-3-yl]benzene) carrier balance, exhibits the attractive electroluminescent (EL) performance with both ηEQEmax= 3.11% and almost negligible efficiency-roll-off.

Rhodamine 6G-Labeled Pyridyl Aroylhydrazone Fe(II) Complex Exhibiting Synergetic Spin Crossover and Fluorescence

Here, we use a pyridinecarbaldehyde rhodamine 6G hydrazone ligand (L) to synthesize an Fe(II) complex 1 for the search of new fluorescent-spin crossover (SCO) materials. Single-crystal structural determinations suggest that the Fe(II) ion is chelated by two ring-opened ligands (L-o) to form a FeN4O2 coordination environment, and intermolecular π---π contacts of the xanthene groups connect the adjacent molecules to form a supramolecular one-dimensional chain. Magnetic susceptibility measurements on complex 1 show that three-step SCO takes place in the temperature range of 120-350 K, and its desolvated form 1-d exhibits SCO around room temperature ( Tc↑ = 343 K and Tc↓ = 303 K) with a wide hysteresis loop of 40 K. Moreover, complex 1-d displays light-induced excited spin-state trapping phenomenon. Intriguingly, the fluorescence intensity of the maximum emission at 560 nm for complex 1-d displays discontinuous variation in the range of 250-400 K, indicative of the occurrence of synergetic fluorescence and SCO.

Two dinuclear oxidovanadium(V) complexes of N2O2 donor amine-bis(phenolate) ligands with bromo-peroxidase activities: Kinetic, catalytic and computational studies

Two dinuclear oxidovanadium(V) complexes [LiVVO(µ2-O)VVO(Li)] (i = 1, H2L1, complex 1 and i = 2 for H2L2, complex 2) of two ONNO donor amine-bis(phenolate) ligands have been synthesized and characterized by X-ray diffraction studies which exhibited distorted octahedral geometry around each V center. In MeCN the complexes exist as dimers as indicated by HRMS studies, however, in the presence of 2 or more equivalents of H+ the dimers turned into monomers, ([LiVV = O]+ which exists in equilibrium with ([LiVV = OH]2+ and evidenced from the shift in λmax from 685 nm to 765 nm for complex 1 and 600 to 765 nm for complex 2. The complexes 1 and 2 efficiently catalyze the oxidative bromination of salicylaldehyde in the presence of H2O2 to produce 5-bromo-salicylaldehyde as the major product with TONs 405 and 450, respectively in the mixed solvent system (H2O:MeOH:THF = 4:3:2, v/v). The kinetic analysis of the bromide ion oxidation reaction indicates a mechanism which is first order in peroxidovanadium complex and bromide ion and limiting first-order on [H+]. The evaluated kBr and kH values are (8.82 ± 0.35) and (65.0 ± 2.23) M−1 s−1 for complex 1 and (6.74 ± 0.19) and (61.87 ± 2.27) M−1 s−1 for complex 2, respectively. The Ka of protonated species ([LiVV = OH]2+ are: Ka = (4.3 ± 0.40) × 10−3 (pKa = 2.37) and (4.7 ± 0.50) × 10−3 (pKa = 2.33) for complex 1 and 2 respectively. On the basis of the chemistry displayed by these model compounds, a mechanism of bromide oxidation and a tentative catalytic cycle have been framed which might be relevant to vanadium haloperoxidase enzymes and supported by DFT calculations.

Structure and spectroscopic properties of nickel benzazolate complexes with hydrotris(pyrazolyl)borate ligand.

The reaction of benzazole ligands 2-(2'-hydroxylphenyl)benzimidazole (Hpbm), 2-(2'-hydroxylphenyl)benzoxazole (Hpbx), and 2-(2'-hydroxylphenyl)benzothiazole (Hpbt), with [Ni(Tp*)(μ-OH)]2 (Tp* = hydrotris(3,5-dimethylpyrazolyl)borate), leads to pentacoordinate nickel complexes [Ni(Tp*)(pbz)] (pbz = pbm (1), pbx (2), pbt (3)). The structures of 1, 2, and 3 were determined by X-ray crystallography. The pentacoordinate nickel complexes have distorted trigonal bipyramidal geometries with Addison's τ parameter values of 0.63, 0.73, and 0.61 for 1, 2 and 3, respectively. The benzazolates are bonded in an η(2)(N,O) fashion to the nickel atoms. DFT calculations are carried out to optimize the structures of the three complexes giving a good agreement with the X-ray structures. The (1)H NMR spectra of complexes 1-3 exhibit sharp isotropically shifted signals. The complete assignment of these signals required an application of two-dimensional {(1)H-(1)H}-COSY techniques. The experimental absorption spectra of the three complexes in chloroform solution each show an intense absorption band in the ultraviolet region ca. 240 nm, followed by three less intense bands, the first two at ∼295 and ∼340 nm, and the last more disperse one, at wavelengths between 360 and 410 nm. The absorption spectra are simulated by TD-DFT and reproduce the main features of the experimental spectra well. The analysis of the electronic transitions by inspection of the frontier molecular orbitals and also the natural transition orbitals allowed us to characterize and assign the observed bands properly. The three complexes are moderately blue luminescent at room temperature, both in the solid state and in solution. Emission spectra at room temperature display broad structureless bands in chloroform solution at 460, 482, and 512 nm for complexes 1, 2 and 3, respectively, and structured emission in solid state with λmax values of 473, 486, and 516 nm. Complexes containing different donor atoms in the benzazole ligand are furthermore observed to give different luminescence responses in the presence of Zn(II), Cd(II), Hg(II), and Cu(II).

Effects of Extended π-Conjugation in Phenanthroline (N∧N) and Phenylpyridine (C∧N) Ligands on the Photophysics and Reverse Saturable Absorption of Cationic Heteroleptic Iridium(III) Complexes

Five new iridium(III) complexes (3,8-R-Phen)Ir(2-(3-R′-phenyl)pyridine)2 (1, R = fluoren-2-yl, R′ = H; 2, R = 7-benzothiazolylfluoren-2-yl, R′ = H; 3, R = H, R′ = fluoren-2-yl; 4, R = H, R′ = 7-benzothiazolylfluoren-2-yl; 5, R = R′ = 7-benzothiazolylfluoren-2-yl) with fluoren-2-yl or 7-benzothiazolylfluoren-2-yl substituent on the 2-phenylpyridine (C∧N) and/or phenanthroline (N∧N) ligands were synthesized and characterized. Their photophysical properties were investigated systematically via UV–vis absorption, emission, and transient difference absorption spectroscopy. Time-dependent density functional theory (TDDFT) calculations were performed to complement the experimental data and aid in our understanding of the characters of optical transitions. In addition, reverse saturable absorption was demonstrated at 532 nm for all complexes using nanosecond laser pulses. All complexes possess a weak low-energy tail that is attributed to 1,3MLCT (metal-to-ligand charge transfer)/1,3LLCT (ligand-to-ligand charge transfer) transitions. The major absorption bands below 475 nm for 1–5 arise from the 1π,π* and intraligand (1ILCT) transitions within the N∧N or C∧N ligands. Attachment of fluoren-2-yl or 7-benzothiazolylfluoren-2-yl substituents on N∧N ligand results in stronger red-shifts of the main absorption band to 400 and 408 nm for 1 and 2, respectively, as compared to 321 and 361 nm in complexes 3 and 4 with the same substituents on the C∧N ligands. In contrast, the 1,3MLCT/1,3LLCT transitions in 1 and 2 are just slightly red-shifted as compared to those in 3 and 4. The emission of complexes 1 and 2 is attributed to the N∧N ligand-centered 3π,π* state with some admixture of 3MLCT/3ILCT/3LLCT characters for 1. In contrast, the emission of 3 and 4 emanates exclusively from the 3MLCT/3LLCT states. For complex 5, which contains 7-benzothiazolylfluoren-2-yl substituents on both the C∧N and the N∧N ligands, the emission predominantly arises from the 3MLCT/3LLCT states with a small portion of N∧N ligand-localized 3π,π* character. All complexes exhibit broadband triplet excited-state absorption in the visible to the near-IR region, with the major absorption bands bathochromically shifted in 1 and 2 as compared to those in 3 and 4. The stronger excited-state absorption leads to dramatic reverse saturable absorption (RSA) at 532 nm for nanosecond laser pulses. The RSA strength decreases as 5 ≈ 2 > 4 ≈ 1 > 3, which is primarily determined by the ratio of the triplet excited-state absorption cross section relative to that of the ground state. Extended π-conjugation in the N∧N ligand obviously increases the RSA of complexes 1, 2, and 5 in comparison to those with π-conjugated substituents only on the C∧N ligands (3 and 4).

Theoretical studies on the spectroscopic properties of a series of palladium (II) complexes with 1-allyl-3-(2-pyridyl)thiourea

To explore the spectroscopic properties, a series of palladium complexes are investigated theoretically through density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations. Full geometry optimizations of 1-allyl-3-(2-pyridyl)thiourea (APTU) and its corresponding Pd (II) complexes [Pd(APTU)Cl2] (A), trans-[Pd(APTU)2]2+ (B), cis-[Pd(APTU)2]2+ (C), together with two thiolic tautomeric APTU-based Pd (II) complex cis-[Pd(APTU)2] (D) and trans-[Pd(APTU)2] (E) are carried out at the B3LYP, B3PW91, and M06 levels. All of them present slightly distorted square-planar geometries. On the basis of the optimized geometries, the absorption spectra in ethanol are evaluated by using three TD-DFT methods with the PCM model. Experimental absorption spectra are well reproduced by our time-dependent density functional theory calculations. Both UV–vis absorption peaks at 219.64 and 254.80nm for complex A are mainly attributed to (p,π,d)→π* with a mixed character of intraligand charge-transfer (ILCT)/ligand–ligand charge-transfer (LLCT)/metal-ligand charge-transfer (MLCT) transitions. Another weak absorption band of complex A is located at 313.17nm largely originated from HOMO−6 to LUMO transition. There are two isomers with small energy difference for [Pd(APTU)2]2+, i.e., trans-[Pd(APTU)2]2+ (B) and cis-[Pd(APTU)2]2+ (C). Only when both isomers are considered, four absorption peaks can be obtained, which is in line with the experimental results. The absorption peaks of complexes D and E present obvious red shift that is associated with their lower HOMO–LUMO gap (ΔE|HOMO–LUMO|) among five complexes. Differences and similarities in molecular orbitals and electronic transition characters for five complexes are discussed in detail.

Polyelectrolyte complex nanoparticles from chitosan and poly(acrylic acid) and Polystyrene‐block‐poly(acrylic acid)

AbstractInterpolymer polyelectrolyte complexes of chitosan (CS) with poly(acrylic acid) homopolymers and polystyrene‐block‐poly(acrylic acid) diblock copolymers were prepared and characterized. The influence of the positive/negative charge balance (charge ratio), pH, and ionic strength were thoroughly studied by dynamic light scattering. The existence of a strong polyelectrolyte effect was also highlighted in this study. Domains of stability, in which nanoparticle sizes are smaller than 100 and 200 nm for complexes of CS with the homopolymer and copolymer, respectively, were identified and confirmed by scanning electron microscopy and atomic force microscopy. The charged nature of the surface of the nanoparticles was evidenced by Zeta potential measurements. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

Structural and electronic properties of luminescent copper(i) halide complexes of bis[2-(diphenylphosphano)phenyl] ether (DPEphos). Crystal structure of [CuCl(DPEphos)(dmpymtH

Heteroleptic copper(I) halide complexes containing the bis[2-(diphenylphosphano)phenyl]ether (DPEphos) ligand and the heterocyclic thioamides pyridine-2(1H)-thione (py2SH), pyrimidine-2(1H)-thione (pymtH) or 4,6-dimethylpyrimidine-2(1H)-thione (dmpymtH) have been synthesized and characterized by (1)H-NMR, IR spectroscopy, elemental analyses and melting point determinations. The complexes can be readily obtained by the addition of the thione ligand to a CuX-diphosphane adduct in dichloromethane-ethanol solution. The molecular structure of [CuCl(DPEphos)(dmpymtH)] complex has been established by single-crystal X-ray diffraction. The structure features a tetrahedral copper(I) center with two phosphorus atoms from the chelating diphos ligand, one halogen atom and the exocyclic sulfur atom of the heterocyclic thioamide unit. The complexes are strongly emissive in the solid state at ambient temperature. DFT and TD-DFT calculations were employed to study the structural, electronic and photophysical properties of the novel complexes. Electronic absorption spectra show two broad bands in the regions 275-290 and 380-398 nm of mixed MLCT/IL character. Intense blue-green emission is observed in the region 500-558 nm for complexes having py2SH or dmpymtH thione ligands. The emitting first triplet excited state, T(1) is mainly localized on the thione ligand.

Optical properties of binuclear zinc (II) macrocyclic complexes derived from 4-methyl-2,6-diformylphenol and 1,2-diaminobenzene

In this work, we present the synthesis and optical study of the binuclear zinc(II) macrocyclic complexes, derived from 4-methyl-2,6-diformylphenol and 1,2-diaminobenzene (H 2L). Two zinc macrocyclic complexes with different anions were prepared and characterized: [Zn 2LCl 2]·H 2O ( 1) and [Zn 2L](NO 3) 2 ( 2). The complexes are emissive, both in the solid state and in solution at room temperature. Spectroscopic properties of the macrocyclic complexes were investigated using stationary and time resolved methods in solutions of dimethylsulfoxide (DMSO), and in solid state. DMSO solutions show two emission bands centered at 480 and 521 nm for complex ( 1), and at 527 nm with a shoulder at 480 nm for ( 2). The emission spectra of these compounds in solid state show a red shifted band, presenting the maxima at 565 nm for ( 1) and 575 nm for ( 2). The emission lifetimes for these compounds are very short, viz. 650 and 480 ps for macrocycles ( 1) and ( 2), respectively.

Synthesis, structures and spectroscopic properties of platinum(II), copper(I) and zinc(II) complexes bearing 4-( p-dimethylaminophenyl)-6-phenyl-2,2′-bipyridine ligand

The reactions of 4-( p-dimethylaminophenyl)-6-phenyl-2,2′-bipyridine ( HL) with three metal salts of platinum(II), copper(I) and zinc(II) provide the new complexes [Pt(L)(PPh 3)]ClO 4 ( 1), [Cu(HL) 2]BF 4 ( 2), [Cu(HL)(PPh 3)]BF 4 ( 3) and [Zn(HL) 2](ClO 4) 2 ( 4). All the structures of these four complexes have been characterized by single crystal X-ray diffraction, and their spectroscopic properties were investigated. Especially for complex 1, upon protonation, the excited state can be tuned from the intraligand charge transfer (ILCT) to the metal-to-ligand charge transfer (MLCT), and such switching in the excited state is acid/base reversible. The time-dependent density functional theory (TD-DFT) calculation was used to interpret the absorption spectra of complex 1, and the calculated result is consistent with those of experiments results. In contrast with 1, the lowest energy absorption at 410–650 nm of complexes 2 and 3 can be assigned to MLCT excited state. In solid state or solution complex 4 exhibits intense photoluminescence attributed to a ILCT transition in nature.

Mononuclear and binuclear sandwich copper(II) complexes with poly(pyrazolyl)borate ligands: Syntheses, structures and properties

A series of Cu(II) complexes Cu 2[μ-pz] 2[HB(pz) 3] 2 ( 1), Cu[H 2B(pz) 2] 2 ( 2), Cu[HB(pz) 3] 2 ( 3), Cu[HB(pz Me2) 3] 2 ( 4), Cu[B(pz) 4] 2 ( 5) (pz = pyrazole), have been synthesized and characterized by elemental analysis, IR, UV–vis, X-ray diffraction, thermal analysis and theoretical analysis. The IR spectra give the Cu–N vibration modes at 322, 366, 344, 387, and 380 cm −1 in complexes 1– 5, respectively. The UV spectra show all the complexes have same UV absorption at 232 nm; there is another band at 332 nm for complexes 1, 2 and 4, while for complexes 3 and 5, the bands are at 272 and 308 nm, respectively. Complex 1 has a binuclear structure in which two pyrazole ligands bridge two Cu-Tp units. In 2– 5, the Cu(II) centers are coordinated with dihydrobis(pyrazolyl)borate (Bp), hydrotris(pyrazolyl)borate (Tp), hydrotris(3,5-Me2pyrazolyl)borate (Tp′), tetrakis(pyrazolyl)borate (Tkp) respectively to form a mononuclear structure. The results of thermal analysis for complexes 1– 5 are discussed too.