Photophysical Properties Of Complexes Research Articles

A Molecular Triangle as a Precursor Toward the Assembly of a Jar-Shaped Metallasupramolecule

The reaction of Re2(CO)10 and 1,1′-carbonyldiimidazole in toluene afforded the molecular triangle [Re3(μ2-Im)3(CO)12] (1; Im = imidazolate). This air-stable complex 1 acted as a precursor, which could then be further transformed into the complex [{Re(CO)3}3(μ2-Im)3(μ3-L)] (2; L = 1,3,5-tris(benzimidazol-1-ylmethyl)-2,4,6-trimethylbenzene) upon reaction with the flexible ligand L under solvothermal conditions. Complex 2 can also be produced directly in a one-pot reaction from Re2(CO)10, 1,1′-carbonyldiimidazole, and the flexible ligand L. A single-crystal X-ray diffraction analysis showed that compound 1 has a triangular-shaped structure, which is the smallest rhenium triangle known, as of this writing. Complex 2 adopted a jar-shaped structure. The photophysical properties of complexes 1 and 2 were studied.

Cyclometallated iridium(III) complex with the norbornene-substituted pyrazolonate ligand and related copolymers: syntheses, structures, and photophysical properties

New cyclometallated iridium(III) complex (NBEpz)Ir(Ppy)2 · 2CH2Cl2 (I) (NBEpzH is 1-phenyl-3-methyl-4-(5-bicyclo[2.2.1]hept-5-en-2-yl)-5-pyrazolone, PpyH is 2-phenylpyridine) is synthesized and structurally characterized. Compound I undergoes metathesis polymerization and forms new iridium-containing copolymers. The photophysical properties of complex I and related copolymers are studied.

Hetero-trinuclear near-infrared (NIR) luminescent ZnLn2 (Ln = Nd, Yb or Er) complexes based on monomer ZnL Schiff-base precursor and o-vanillin

Abstract With the monomer [Zn(L 1 )(H 2 O)] ( 1 ) complex in situ formed by the deprotonated hexadentate Salen-type Schiff-base ligand H 2 L 1 ( H 2 L 1 = N,N′-bis(3-methoxy-salicylidene)cyclohexane-1,2-diamine) and Zn(NO 3 ) 2 as the precursor, series of the hetero-trinuclear ZnLn 2 complexes [ZnLn 2 (L 1 ) 2 (L 2 )(NO 3 ) 2 Cl] (Ln = Nd, 2 ; Ln = Yb, 3 ; Ln = Er, 4 or Ln = Gd, 5 ) were obtained from the further reaction with LnCl 3 (Ln = Nd, Yb Er or Gd) and the second o -vanillin ( HL 2 ) ligand, respectively. The photophysical properties of complexes 2 – 4 showed that the characteristic near-infrared (NIR) luminescence of Ln 3 + ions with two emission centers and emissive lifetimes in microsecond ranges, was sensitized from the excited state (both 1 LC and 3 LC) of mixed H 2 L 1 – HL 2 ligands.

Synthesis, Characterization, Photoluminescence, and Simulations of a CCC-NHC-Supported Pt2Ag2 Mixed-Metal Cluster Containing a PtAg2 Metallacyclopropane

The pincer CCC-bis(NHC)-supported Pt(II) complex 2, (1,3-bis(N-((trimethylsilyl)methyl)imidazol-2-ylidene)-2-phenylene)chloroplatinum(II), was prepared and was reacted with excess or stoichiometric silver(I) trifluoroacetate. The reaction with excess yielded the Pt2Ag2 cluster 3, which to our knowledge contains the first unsymmetrically substituted example of a PtAg2 metallacyclopropane, as revealed by X-ray crystallography. A distorted-octahedral configuration was also found in the coordination sphere of one of the silver atoms. Multiple weak hydrogen bonds (WHB) including C–H···O, C–H···F, and C–F···π interactions were identified in the lattice of cluster 3. The unique structure of cluster 3 was simulated using density functional theory (DFT), which revealed that it was thermodynamically favored over the more expected configurations. The stoichiometric reaction with Ag(OCCF3) afforded the simple ligand exchange product (1,3-bis(N-((trimethylsilyl)methyl)imidazol-2-ylidene)-2-phenylene)(trifluoroacetato)platinum(II) (4). The reaction of stoichiometric or excess AgOAc afforded only the monomeric product of simple ligand metathesis, (1,3-bis(N-((trimethylsilyl)methyl)imidazol-2-ylidene)-2-phenylene)(acetato)platinum(II) (5). This observation is consistent with the hypothesis that the weak hydrogen bond network and the increased Lewis acidity of Ag(OCCF3) are significant contributors to the structure of cluster 3. The photophysical properties of complexes 2–5 have been investigated. The emission color of the solution of cluster 3 was found to be concentration dependent.

Synthesis, crystal structure, photoluminescence and theoretical studies of a series of copper(I) compounds based on imidazole derivatives

Two mononuclear and one binuclear Cu(I) complexes that contain imidazole derivative ligands including 2-(2′-pyridyl)imidazole (L1), 2-(2′-pyridyl)benzimidazole(L2), and 2,6-bis (benzimidazol-2yl)-pyridine (L3) were synthesized. The formulas of these complexes are [CuL1(PPh3)2][BF4] (1), [CuL2(PPh3)2][BF4] (2), [Cu2(L3)2(PPh3)2][BF4]2 (3), respectively. The crystal structures of complexes 1–3 have been determined by single-crystal X-ray diffraction analyses. The Cu(I) ions in the complexes have a distorted tetrahedral geometry. Photophysical properties of complexes 1–3 were systematically studied. These complexes maximum emission are mainly concentrated in the 623–680nm. An electroluminescent (EL) device using 2 as the emitter was fabricated. The device produced a red emission which matches with the PL spectrum. However, the EL device of 2 is unfavorable. The absorption properties of complexes 1 and 2 were theoretically analyzed by time-dependent density functional theory (DFT).The calculated results are in good agreement with the experimental data.

Blue-Green Luminescent Rhenium(I) Tricarbonyl Complexes with Pyridine-Functionalized N-Heterocyclic Carbene Ligands

Five rhenium(I) tricarbonyl chloride complexes with pyridine-functionalized N-heterocyclic carbenes, Re(CO)3(L)Cl (L = 3-methyl-1-(2-pyridyl)imidazol-2-ylidene (1), 3-methyl-1-(2-picolyl)imidazol-2-ylidene (2), 3-methyl-1-(2-pyridyl)benzimidazolin-2-ylidene (3), 3-methyl-1-(2-picoyl)benzimidazolin-2-ylidene (4), 1-methyl-4-(2-pyridyl)-1,2,4-triazoline-5-ylidene (5)), have been synthesized by silver carbene transmetalation and characterized by elemental analysis, 1H NMR, 13C NMR, and IR spectra. The molecular structures of 3–5 have been determined by single-crystal X-ray diffraction. The electrochemical and photophysical properties of complexes 1, 3, and 5 have been studied. In both degassed CH2Cl2 solution and the solid state at room temperature or 77 K, the emission wavelengths (465–511 nm) of complexes 1, 3, and 5 lie in the blue-green region, which are rare in contrast to the reported rhenium(I) tricarbonyl complexes. The photoluminescence lifetime decays of Re(I) complexes 1, 3, and 5 were measured, a...

Excited states of the green fluorescent protein chromophore: Performance of ab initio and semi‐empirical methods

AbstractThe complex photophysical properties of fluorescent proteins give rise to a wide field of applications as markers in molecular biology. Understanding these properties is essential for rational genetic engineering of new fluorescent proteins. Here, theoretical models are required to support the interpretation of structural and spectroscopic experimental data. This requires the accurate and reliable prediction of excited‐state features of the chromophore and its interactions with the protein matrix. Here, we compare calculations of absorption and emission energies of semi‐empirical (OM2/MRCI, ZINDO/S, and TD‐DFTB) and ab initio (SORCI, CC2, and TDDFT) approaches for the HBDI chromophore in vacuo and wild‐type green fluorescent protein (GFP) using QM/MM models. We discuss the influence of electrostatic fields, the chromophore geometry, the size of the QM region, and methodological aspects, in particular charge‐transfer states in TDDFT and the applicability of real‐space TDDFT codes. We revisit previous opposing theoretical studies and benchmark gas‐phase measurements.magnified image Proton transfer wire of wild‐type green fluorescent protein (wt‐GFP).

New iridium cyclometallated complexes with potential application in OLED

The photophysical and electrochemical properties of cyclometallic cationic iridium complexes that also contain bipyridine type ligands have been investigated in this work. The effect on the photophysical properties of the complexes on the presence of aliphatic long chain or branched substitution was analyzed. The complexes show photoluminescence maxima in the green-blue region of the visible spectrum, with acceptable quantum yields and lifetime, showing in this way potentiality to be tested in OLED devices.

Trinuclear copper(I) acetylide complexes bearing carbonyl moiety: Synthesis, characterization, and photophysical properties

A series of trinuclear copper(I) acetylide complexes with carbonyl moiety, [Cu 3(μ-dppm) 3(μ 3-η 1-C CC(O)R) 2](ClO 4) (R = H ( 1), CH 3 ( 2), OCH 3 ( 3), NH 2 ( 4), NEt 2 ( 5)) (dppm = bis(diphenylphosphino)methane), have been synthesized and characterized. The crystal structures of [Cu 3(μ-dppm) 3(μ 3-η 1-C CC(O)CH 3) 2](ClO 4) ( 2) and [Cu 3(μ-dppm) 3(μ 3-η 1-C CC(O)NH 2) 2](ClO 4) ( 4) were determined by X-ray diffraction. The photophysical properties of complexes 1− 5 have been studied. Complexes 1− 5 show luminescence both in the solid state and in acetonitrile solution at 298 K, and their emission energies are in the order: 5 > 4 > 3 > 2 > 1. Density function theory (DFT) calculations at the hybrid Perdew, Burke, and Ernzerhof functional (PBE1PBE) level were performed on model complex 1 to elucidate the emission origin of complexes 1− 5.

Structural diversity and properties of M(ii) phenyl substituted pyrazole carboxylate complexes with 0D-, 1D-, 2D- and 3D frameworks

Eight new metal complexes with two kinds of phenyl substituted pyrazole carboxylic acid, [Ni(HL1)2(H2O)2] (1), [Cu(HL1)2(H2O)2] (2), [Zn(HL1)2] (3), [Ni(HL2)2(H2O)2] (4), [Ni(HL2)2(HL3)2] (5), [Cu(HL2)2]·2H2O (6), [Zn(HL2)2] (7), [Zn2(HL2)2(L2)] (8) [H2L1 = 5-phenyl-1H-pyrazole-3-carboxylic acid; H2L2 = 3-phenyl-1H-pyrazole-4-carboxylic acid; HL3 = 3-phenyl-1H-pyrazole] were prepared by hydro/solvothermal reactions and structurally characterized. Complexes 1 and 2 have monomeric structures; 3 and 4 exhibit 1-D zig-zag chains; 5 and 6 possess 2D layer structures consisting of rhomboid grids; 7 features a 2-fold interpenetrated 3-D diamondoid framework; while complex 8 holds a 3-D NaCl-like framework. Hydrogen bonding and aromatic π–π stacking interactions link the eight complexes into 2-D (1–3) or 3-D (4–8) supramolecular networks, of which 5, 6 and 8 contain single, single and double-stranded helical chains, respectively. The thermal stabilities of complexes 1–8 and photophysical properties of complexes 3 and 7 were investigated.

Photophysical properties of a new ternary europium complex with 2-thenoyltrifluoroacetone and 5-nitro-1,10-phenanthroline

A ligand, 5-nitro-1,10-phenanthroline (phenNO 2), was synthesized. Its Eu(III) complex with 2-thenoyltrifluoroacetone (HTTA) was prepared and characterized by elemental analysis, IR and 1H NMR spectra. The photophysical properties of the complex were studied in detail by using UV, luminescence spectra, luminescence lifetime and quantum yield. The complex exhibited nearly monochromatic red emission at 612 nm, a remarkable luminescence quantum yield at room temperature (36.0%) upon ligand excitation and a long 5D 0 lifetime (458 μs), which indicated that the ligand phenNO 2 could sensitize the luminescence of Eu(III) ion efficiently.

Photophysical properties of lanthanide complexes with 5-nitro-1,10-phenanthroline

Five novel lanthanide (Eu3+, Tb3+, Sm3+, Dy3+, and Gd3+) complexes with 5-nitro-1,10-phenanthroline (phenNO2) have been synthesized and characterized by elemental analysis, IR, UV, and luminescence spectra. The triplet state energy of phenNO2 was determined to be 20,048 cm−1 via the phosphorescence spectra of phenNO2 and its gadolinium complex. The photophysical properties of these complexes indicated that the triplet state energy of the ligand is suitable for the sensitization of the luminescence of Eu3+ and Sm3+, especially the former. 5-Nitro-1,10-phenanthroline acts as photon antenna able to transfer energy to Eu(III) ion effectively. Therefore, the intense typical fluorescence of the Eu(III) ions was observed

Binuclear aluminum complex as an efficient orange emitter in single-layer electroluminescent devices

A binuclear aluminum complex with a chelating anilido-imine conjugated Schiff base ligand, 1,4-{ o-C 6H 4[N(2,6- i Pr 2C 6H 3)][CH N]Al(CH 3) 2} 2C 6H 4 (3), was synthesized from the alkane elimination reaction of trimethylaluminum with the free ligand, 1,4-{ o-C 6H 4[NH(2,6- i Pr 2C 6H 3)][CH N]} 2C 6H 4 (2), at room temperature. The photophysical properties of complex 3 were briefly examined and it was found that complex 3 displays bright orange luminescence in solution and in solid state. Electroluminescent devices were fabricated by doping complex 3 in polymer blend host of poly(vinylcarbazole) and 2- tert-butylphenyl-5-biphenyl-1,3,4-oxadiazol using simple solution spin-coating technique. Efficient orange light emission was obtained from the fabricated single-layer organic light-emitting devices with a maximum current efficiency of 3.2 cd/A.

Synthesis and characterization of neutral iron(ii) and ruthenium(ii) complexes with the isocyanotriphenylborate ligand

By reacting metal cyanide complexes with NaBPh(4) in the presence of acid at room temperature, a new class of neutral isocyanotriphenylborate-containing complexes trans-Ru(L)(4)(CNBPh(3))(2) (L = pyridine, 1; 4-methylpyridine, 2; 4-tert-butylpyridine, 3), cis-Ru(bipy)(2)(CNBPh(3))(2) (4, bipy = 2,2'-bipyridine) and cis-M(phen)(2)(CNBPh(3))(2) (M = Ru, 5; M = Fe, 6; phen = 1,10-phenanthroline) have been synthesized. These new complexes are characterized by IR, UV spectroscopy and single-crystal X-ray diffractions. The electron withdrawing triphenylborate group on the isocyanide ligands has a pronounced effect on the photophysical properties of complexes 1-6 in comparison with other ruthenium(II) and iron(II) isocyanide complexes. The excitation energies corresponding to metal-to-ligand charge transfer (MLCT) shift to higher energies while the (3)MLCT emissions are quenched at room temperature.

Preparation and photophysical studies of copper(I) and ruthenium(II) complexes of 4,4′-bis(3,5-dimethoxyphenyl)-6,6′-dimethyl-2,2′-bipyridine

We report the synthesis of a new ligand, 4,4′-bis(3,5-dimethoxyphenyl)-6,6′-dimethyl-2,2′-bipyridine, optimised for binding to copper(I) and with pendant functionality that can eventually be developed into metallodendritic structures. The synthesis and photophysical properties of complexes with copper(I) and ruthenium(II) are reported. The solid state structure of the complex [Cu( 1) 2][PF 6] · MeCN ( 1 = 4,4′-bis(3,5-dimethoxyphenyl)-6,6′-dimethyl-2,2′-bipyridine) is also described.

Photophysical Properties of Novel Ternary Lanthanide Complexes with Long Chain Mono-L Cis-Butene Dicarboxylate (L = Hexadecyl, Octadecyl and Eicosyl) and 2,2’-Bipyridyl (or 1,10-Phenanthroline)

Maleic anhydride was modified by long chain alcohol (1-hexadecanol, 1-octadecanol and 1-eicosanol) to a novel sort of corresponding long monoester mono-L cis-butene dicarboxylate (L = hexadecyl, octadecyl and eicosyl), i.e. monohexadecyl cis-butene dicarboxylate (MAH), monooctadecyl cis-butene dicarboxylate (MAO), and monoeicosyl cis-butene dicarboxylate (MAE), respectively. Then the some novel ternary lanthanide (Eu3+, Tb3+) complexes with the as-derived long chain monoester and assistant nitrogen-heterocyclic ligands (2,2'-bipyridyl (bipy) and 1,10-phenanthroline (phen)) were synthesized and characterized by elemental analysis and IR spectra. The photophysical properties of these complexes were studied in detail with ultraviolet absorption spectra, luminescent excitation and emission spectra and luminescent lifetimes, indicating that the intramolecular energy transfer mechanism runs smoothly within these ternary complexes in terms of sensitized functions of bipy and phen and strong characteristic red or green emissions of Eu3+ or Tb3+ have been achieved.

Photophysical properties of praseodymium complexes with aromatic carboxylic acids: Double light conversion both in ultraviolet and visible region

A series of luminescent praseodymium complexes with different aromatic carboxylic acids have been synthesized and characterized. The photophysical properties of these complexes have been studied with ultraviolet spectra, phosphorescence spectra and fluorescence spectra. Ultraviolet absorption spectra show that the praseodymium complexes systems with aromatic carboxylate form the more extensive conjugated systems to be suitable for the distribution of electron in the whole coordination environment, resulting in the energy decrease and red-shifts of ultraviolet spectral bands. Phosphorescence spectra suggest that excited triplet state of aromatic carboxylic acids, which can indicate the energy match and intermolecular energy transfer process between the excited triplet state of ligands and the resonant emissive energy level of Pr ions. The emission spectra of all praseodymium complexes show two emission peaks under the excitation band of 245 nm at about 395 and 595 nm, respectively, while one peak at about 595 nm under 415 nm excitation, which attributed to be 1S 0 → 1I 6 (395 nm) transition and the characteristic emission 1D 2 → 3H 4 (595 nm) transition of Pr 3+ ion. The 1S 0 → 1I 6 transition can be speculated to belong to the transition of charge transfer state, and the 1D 2 → 3H 4 can be further proved that there exists an antenna effect in the luminescence of praseodymium with aromatic carboxylic acids. In conclusion, the praseodymium complexes systems can realize the double proton light conversion both in the ultraviolet and visible region, which can be further studied to have potential application.

Spectroscopic Study on the Photophysical Properties of Lanthanide Complexes with Long Chain Mono-Docosyl Phthalate

Ortho phthalic anhydride was modified with long chain alcohol (1-docosanol) to its corresponding monodocosyl phthalate (22-Phth). Subsequently, three novel lanthanide (Eu(3+), Tb(3+), and Dy(3+)) complexes with the long chain monodocosyl phthalate were synthesized and characterized by elemental analysis and Infrared spectra. The photophysical properties of these complexes were studied in detail with ultraviolet-visible absorption spectra, low temperature phosphorescence spectra and fluorescent spectra. The triplet state energy of 22-Phth was determined to be around 25,000 cm(-1) from the maximum phosphorescent peak at 400 nm, suggesting 22-Phth is suitable for the sensitization of the luminescence of Eu(3+), Tb(3+), and Dy(3+). The fluorescence excitation and emission spectra for these lanthanide complexes of the three ligands take agreement with the above predict from energy match principle.

Photophysical properties of novel lanthanide complexes with long chain mono-eicosyl cis-butene dicarboxylate

Maleic anhydride was grafted by long chain alcohol 1-eicosanol to a novel sort of corresponding monoester, mono-eicosyl cis-butene dicarboxylate. Then the four novel ternary lanthanide (Eu 3+, Tb 3+, Dy 3+, Gd 3+) complexes with the as-derived long chain monoester and a second ligand 1,10-phenanthroline were synthesized and characterized by elemental analysis, IR spectra. The photophysical properties of these complexes were studied in detail with ultraviolet absorption spectra, low temperature phosphorescent spectra, fluorescent spectra and luminescent lifetimes, indicating that the intramolecular energy transfer mechanism runs smoothly within these ternary complexes in terms of sensitized functions of 1,10-phenanthroline and strong characteristic green, red or blue emissions of Tb 3+, Eu 3+ or Dy 3+ have been achieved.

Spectroscopic study on the photophysical properties of novel lanthanide complexes with long chain mono-L phthalate (L = hexadecyl, octadecyl and eicosyl)

Ortho-phthalic anhydride was modified with long chain alcohol (1-hexadecanol, 1-octadecanol and 1-eicosanol) to their corresponding mono-L phthalate (L = hexadecyl, octadecyl and eicosyl), i.e. monohexadecyl phthalate (16-Phth), monooctadecyl phthalate (18-Phth), and monoeicosyl phthalate (20-Phth), respectively. Nine novel lanthanide (Eu 3+, Tb 3+ and Dy 3+) complexes with these three mono-L phthalate ligands were synthesized and characterized by elemental analysis and IR spectra. The photophysical properties of these complexes were studied in detail with various spectroscopes such as ultraviolet–visible absorption spectra, low temperature phosphorescence spectra and fluorescent spectra. The ultraviolet–visible absorption spectra show some band shifts with the different chain-length of phthalate monoester and homologous lanthanide complexes. From the low temperature phosphorescent emission, the triplet state energies for these three ligands were determined to be around 22,650 cm −1 (16-Phth), 23,095 cm −1 (18-Phth) and 22,400 cm −1 (20-Phth), respectively, suggesting they are suitable for the sensitization of the luminescence of Eu 3+, Tb 3+ and Dy 3+. The fluorescence excitation and emission spectra for these lanthanides complexes of the three ligands take agreement with the above predict from energy match.