Tetrahydroquinoxaline based squaraines: Synthesis and photophysical properties

Tetrahydroquinoxaline based squaraine dyes synthesized by the condensation reaction between squaric acid and different tetrahydroquinoxaline derivatives are described. The squaraines gave a strong intense peak at 700 nm and were found to exhibit good molar extinction coefficient (>105 M−1 cm−1). Metal binding studies were carried out with different metal ions and it was found that it was selective in the case of copper metal. Using Job's plot it was ascertained that the squaraines bind to the copper metal in the ratio of 2:1.

A novel sheet 4f-3d mixed-metal pyridine dicarboxylate: synthesis, structure, photophysical properties and its transformation to a perovskite oxide

The synthesis, characterization and photophysical properties of a 4f-3d mixed metal compound, Gd(H2O)(3)Co[C5N1H3-(COO)(2)](3), are described; the structure is unique, consisting of sheets with large pores ( ca. 7 angstrom diameter) in the sheets and transforms to a perovskite oxide at moderate temperatures.

Photophysical properties of the fullerenes, C60 and C70

Photophysical properties of the singlet and triplet states of the fullerenes, C60 and C70, have been investigated in toluene, benzene, hexane and ethanol solutions by pico- and nano-second laser flash photolysis techniques. Lifetimes, extinction coefficients, quantum efficiencies of the formation of the excited states and such properties have been determined. True triplet�triplet absorption spectra of C60 and C70 are reported. C60, unlike C70, is found to undergo photoionization in ethanol solution giving solvated electrons.

Spectroscopic, redox and photophysical properties of push-pull fluoroarylporphyrins

Novel fluoroarylporphyrins bearing electron donor dimethylamino groups in the meso-aryl positions and an electron acceptor nitro group on one of the pyrrole carbons exhibit significant solvent dependent fluorescence spectra and time-resolved emission properties. These effects are suggestive of intramolecular charge transfer (ICT) in the singlet excited state of these porphyrins. Electrochemical redox behaviour of these porphyrins showed the presence of substantial donor-acceptor interactions in the nitro-amino porphyrins.

Solvatochromic Effect on the Photophysical Properties of Two Coumarins

The absorption and emission spectra of two coumarins namely 7, 8 benzo-4-azidomethyl coumarin (C-1) and 6-methoxy-4-azidomethyl coumarin (C-2) have been recorded at room temperature in solvents of different polarities. The ground state dipole moments (mu(g)) of two coumarins were determined experimentally by Guggenheim method. The exited state (mu(e)) dipole moments were estimated from Lippert's, Bakhshievs and Chamma-Viallet's equations by using the variation of Stoke's shift with the solvent dielectric constant and refractive index. The ground and excited state dipole moments were calculated by means of solvatochromic shift method and also the excited state dipole moments are determined in combination with ground state dipole moments. It was observed that dipole moments of excited state were higher than those of the ground state, indicating a substantial redistribution of the pi-electron densities in a more polar excited state for two coumarins.

Influence of Side-Chain on Structural Order and Photophysical Properties in Thiophene Based Diketopyrrolopyrroles: A Systematic Study

In this work, we have synthesized a series of TDPP derivatives with different alkyl groups such as n-hexyl (-C6H13) 3a, 2-ethylhexyl (-(2-C2H5)C6H12) 3b, triethylene glycol mono methyl ether (-(CH2CH2O)(3c)H-3, TEG) 3c, and octadodecyl (-(8-C8H17)C12H22) 3d. N,N dialkylation of Othiophene-diketopyrrolopyrrole (TDPP, 1) strongly influences its solubility, solid state packing, and structural order. These materials allow us to explicitly study the influence of alkyl chain on solid state packing and photophysical properties. TDPP moiety containing two different alkyl groups 3e (TEG and 2-ethylhexyl) and 3f (TEG and n-hexyl) were synthesized for the first time. The absorption spectra of all derivatives exhibited a red shift in solid state when compared to their solution spectra. The type of alkyl chains leads to change in the optical band gaps in solid state. The fluorescence study reveals that TDPP derivatives have strong pi-pi interaction in the solid state and the extent of bathochromic shift is due to combination of intramolecular interaction and formation of aggregates in solid state. This behavior strongly depends on the nature of alkyl chain. The presence of strong C-H center dot center dot center dot O inter chain interactions and CH-pi interactions in solid state exhibits strong influence on the photophysical properties of TDPP chromophore.

Revisiting borylanilines: unique solid-state structures and insight into photophysical properties

The structure and photophysical properties of two known borylanilines, 4-(dimesitylboryl)aniline (1) and 4-(dimesitylboryl)-3,5-dimethylaniline (2), have been investigated. 1 and 2 have similar donor and acceptor centers but differ in their molecular conformations. Compounds 1 and 2 have been structurally characterized, and they exhibit a rare form of intermolecular N-H - - -pi electrostatic interactions. The structure and photophysical properties of 1 and 2 are discussed in the context of computational results.

Effect of Chalcogens on Electronic and Photophysical Properties of Vinylene-Based Diketopyrrolopyrrole Copolymers

Three vinylene linked diketopyrrolopyrrole based donor acceptor (D-A) copolymers have been synthesized with phenyl, thienyl, and selenyl units as donors. Optical and electronic properties were investigated with UV-vis absorption spectroscopy, cyclic voltammetry, near edge X-ray absorption spectroscopy, organic field effect transistor (OFET) measurements, and density functional theory (DFT) calculations. Optical and electrochemical band gaps decrease in the order phenyl, thienyl, and selenyl. Only phenyl-based polymers are nonplanar, but the main contributor to the larger band gap is electronic, not structural effects. Thienyl and selenyl polymers exhibit ambipolar charge transport but with higher hole than electron mobility. Experimental and theoretical results predict the selenyl system to have the best transport properties, but OFET measurements prove the thienyl system to be superior with p-channel mobility as high as 0.1 cm(2) V-1 s(-1).

Spectral characterizations and photophysical properties of one-step synthesized blue fluorescent 4 `-aryl substituted 2,2 `:6 `,2 `'-terpyridine for OLEDs application

We have synthesized a series of 4'-aryl substituted 2,2':6',2 `'-terpyridine (terpy) derivatives, namely 4'-(4-methylphenyl)-2,2':6',2 `'-terpyridine (C-1), 4'-(2-furyl)-2,2':6'2 `'-terpyridine (C-2), and 4'-(3,4,5-trimethoxyphenyl)-2,2':6',2 `'-terpyridine (C-3). The synthesized terpy compounds were characterized by elemental analyses, FTIR, NMR (H-1 and C-13), and ESI-Mass spectrometry. Photophysical, electrochemical and thermal properties of terpy compounds were systematically studied. Maximum excitation band was observed between 240 and 330 nm using UV-visible spectra, and maximum emission peaks from PL spectra were observed at 385, 405 and 440 nm for C-1, C-2 and C-3 respectively. Fluorescence lifetime (tau) of the fluorophores was found to be 035 and 1.55 ns at the excitation wavelength of 406 nm for C-1 and C-2 respectively, and tau value for C-3 was found to be 0.29 ns at the excitation wavelength of 468 nm. We noticed that the calculated values of HOMO energy levels were increased from 5.96 (C-1) to 6.08 (C-3) eV, which confirms that C-3 derivative is more electrons donating in nature. The calculated electrochemical band gaps were 2.95, 2.82 and 3.02 eV for C-1, C-2 and C-3 respectively. These blue fluorescent emitter derivatives can be used as an electron transport and electroluminescent material to design the blue fluorescent organic light emitting diode (OLED) applications. (C) 2015 Elsevier B.V: All rights reserved.

Synthesis, photophysical properties, and theoretical studies on pyrrole-containing bromo Re(I) complex

Two bromo rhenium(I) carbonyl complexes with the formula of [Re(CO)(3)(L)Br], where L = 1,10-phenanthroline (Phen-Re) and 5-(1H-pyrrol-1-yl)-1,10-phenanthroline (Pyph-Re), were successfully synthesized with the aim to analyze the effect of the pyrrole (Py) moiety on the photophysical properties of Pyph-Re. It was found that the triplet metal-to-ligand charge-transfer d pi (Re) --> pi*(N-N) emission of Phen-Re and Pyph-Re centered at ca. 527 nm with the luminescence quantum yield (LQY) of 0.015 and ca. 578 nm with the LQY of 0.011, respectively. At the same time, the geometrical structures of the ground state and the absorption spectral properties of Phen-Re and Pyph-Re were also calculated with the 6-31G* basis set employed on C, H, N, O, and Br atoms, and LANL2DZ adopted on Re atom.

Tuning of emission: Synthesis, structure and photophysical properties of imidazole, oxazole and thiazole-based iridium (III) complexes

Three new iridium (III) complexes with two cyclometalated (CN)-N-boolean AND ligands (imidazole, oxazole and thiazole-based, respectively) and one acetylacetone (acac) ancillary ligand have been synthesized and fully characterized. The structure of the thiazole-based complex has been determined by single crystal X-ray diffraction analysis. The Ir center was located in a distorted octahedral environment by three chelating ligands with the N-N in the trans and C-C in the cis configuration. By changing the hetero-atom of (CN)-N-boolean AND ligands the order S, O and N, a marked and systematic hypsochromic shift of the maximum emission peak of the complexes was realized. The imidazole-based complex emits at a wavelength of 500 nm, which is in the blue to green region. The tuning of emission wavelengths is consistent with the variation of the energy gap estimated front electrochemistry results. An electroluminescent device using the thiazole-based complex as a dopant in the emitting layer has been fabricated. A highly efficient yellow emission with a maximum luminous efficiency of 9.8 cd/A at a current density of 24.2 mA/cm(2) and a maximum brightness of 7985 cd/m(2) at 19.6 V has been achieved.

Preparation, characterization and photophysical properties of layered zirconium bis(monohydrogenphosphate) intercalated with rare earth complexes

Two kinds of rare earth (RE) complexes were intercalated into zirconium bis(monohydrogenphosphate) (alpha -ZrP) by exchanging the RE complexes into the p-methyoxyaniline (PMA) preintercalated compound Zr(O3POH)(2). 2PMA (alpha -ZrP . 2PMA). Powder X-ray diffraction patterns reveal that Eu(DBM)(3)phen (DBM: dibenzoylmethane, phen: 1,10-phenanthroline) and Tb(AA)(3)phen (AA: acetylacetone) intercalated into alpha -ZrP . 2PMA. This was confirmed by the UV-visible spectra of both the RE complexes and the assemblies. At the same time, the assemblies have better luminescent properties, and the fluorescent lifetimes of RE3+ in the excited state in the assemblies are much longer than those in the complexes. The stabilities of the assemblies under UV radiation are much better than those of the RE complexes.

Spectroscopic study of the photophysical properties of rare earth ions encapsulated: Water soluble functional calixresorcin[4]arene

A novel macrocyclic compound-water soluble functional calixresorcin[4]arenes-tetra para sulfo-phenylmethyl-calixresorcin[4]are was synthesized for the first time. The photophysical properties of terbium and europium ions encapsulated in the macrocyclic ligand were studied in detail. The triplet state energy of the calixresorcin[4]arene was determined to be 24400 cm(-1) by the low temperature phosphorescence spectrum and it was found that it can sensitize both terbium ion and europium ion. The possible energy transfer process between the functional calixresorcin[4]arene and the encapsulated Tb3+ and Eu3+ was discussed. The luminescence quantum efficiency of Tb3+- calixresorcin[4]arene was calculated.

Photophysical properties of rare earth complexes with 3,4-furandicarboxylic acid and 1,10-phenanthroline

Synthesis, IR spectra, UV-vis spectra and photophysical properties of Gd3+, Eu3+, Tb3+ complexes with 3,4-furandicarboxylic acid and 1,10-phenanthroline are reported. Intramolecular energy transfer process for these complexes is discussed in detail. It is found that the intramolecular energy transfer efficiency depends on the relative positions between the resonance energy levels of the central rare earth ions and the lowest triplet state energies of ligands.

The synthesis, characterization and photophysical properties of binary and ternary rare earth complexes with N-phenylanthranilic acid and l,l0-phenanthroline

Some novel binary and ternary complexes of rare earth(Gd, Eu,Tb) with N-Phenylanthranilic acid and 1,10-Phenanthroline were synthesized by homogenous precipitation and their compositions were characterized by,elemental analysis, IR spectra and UV-Vis spectra, The triplet state energies of N-Phenylanthranilic acid was determined to be 24 330 cm(-1) with the phosphorescence spectra of its gadolinium complexes and the energy match between the ligand and the central rare earth ions was studied. The photophysical properties such as luminescence properties and intramolecular energy transfer match between rare earth ions and ligands and between ligands were discussed. The result indicates that terbium complexes with N-Phenylanthranilic acid and 1,10-Phenanthroline have excellent luminescence properties.