Photophysical Property of Ternary Complex Eu(DPHA)_3·Phen·2H_2O

One ternary complex of europium with the plant growth regulator HDPHA (2-Hydroxydiphenyl acetic acid) and Phen (1,10-Phenanthroline), Eu(DPHA) 3·Phen·2H 2O, was synthesized and characterized by the elemental analysis and DTA-TG measurement. The photophysical property of the complex was investigated by means of IR spectra, Raman spectrum and laser-exited, high-resolved excitation and emission spectra as well as time-resolved luminescence spectra. The luminescence spectra reveal four Eu 3+ sites with energy difference within 25 cm -1 and local symmetries of C 1 or C 2 or C s in the complex. The energy transfer among the Eu 3+ sites is observed. The 7F J sublevel splitting of the Eu 3+ ion is discussed.

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 Gd 3+ , Eu 3+ , Tb 3+ 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.

Synthesis and Effect of Cation Binding on Photophysical Properties of 1,8-Anthraceno-18-Crown-5

A new type of anthracene crown ether 1, 8-anthraceno-18-crown-5 has been synthesizedand the photophysical properties upon complexation with alkali and alkaline-earth metal canonswere investigated. The fiuorescence quantum yield and lifetime are appreciably enhanced, and thestability constant Ks were determined by fluorometric titration. It was found that the magnitude ofKs is controlled by the size and charge density of the complexed canons.

Synthesis and Photophysical Properties of Fluorene or Carbazole-Based Alternating Copolymers Containing Si and Ethynylene Units in the Main Chain

Alternating copolymerization of 9,9-dihexyl-2,7-dibromofluorene, N-hexyl-2,7-dibromocarbazole (HCz) with diethynyldimethylsilane, diethynyldiphenylsilane, has been investigated using Sonogashira coupling reaction. Photophysical properties of the resulting copolymers were investigated with UV-Vis absorption and photoluminescence spectroscopy. All the copolymers in chloro-form solution showed absorption peaks at 270 - 280 nm with shoulder peaks at around 380 nm derived from π-π* transition or intra-molecular charge transfer through σ-π moiety, respectively. The chloroform solutions of the copolymers showed broad emission peaks at 415 - 425 nm. The emission wave lengths of the copolymers in the solid state (cast film) detected at 360 - 385 nm were remarkably blue-shifted in comparison with those in the chloroform solutions. Hydrosilylation reaction of the copolymers with 1,4-bis(dimethylsilyl)benzene yielded networked copolymers soluble in chloroform, indicating formation of branching polymers. The chloroform solutions of the HCz-based networked copolymers showed bimodal emission derived from new highly energy states in the σ-π conjugation.

Synthesis and Photophysical Properties of Dy^(3+) and Gd^(3+) Polymeric Complexes with Functionalized Polybenzimidazole Containing β-Diketone Side Group

The polymeric ligand PBIa （functionalized polybenzimidazole containing β-diketone side group） was successfully synthesized via the reaction of polybenzimidazole （PBI） with 3-Br-acetylacetone in DM SO solvent using Nail as the deprotonation reagent. Its corresponding polymeric complexes of Dy^3＋ and Gd^3＋ were prepared and characterized by FT-IR, ^1H NMR, molar conductance measurements, and thermal analysis. The photoluminescence properties and the probable mechanism of the Dy and Gd complexes were studied. The measurement and analysis of the thermal properties showed that these were thermal stable.

Synthesis and photophysical properties of metal anthraquinone phthalocyanine

A novel anthraquinone phthalocyanine AI（Ⅲ） 4 and Co（Ⅱ） 5 were synthesized and characterized by elemental analysis, IR UV/ vis, ^1H NMlL HPLC and MS. The photophysical properties of the two metal complexes were studied and compared by fluorescence spectrum method.

PHOTOPHYSICAL PROPERTIES OF THE ASYMMETRIC PENTAAZADENTATE PORPHYRIN-LIKE MACROCYCLES

The porphyrin-like macrocycles and their metal complexes are s novel family of photoresponsive molecules.The properties of the excited states,both singlet and triplet are investigated by the stationary and transient processes.

Synthesis and characterization of X-shaped oligo(para-phenylene) derivatives functionalized with fluorene ethynylene

A series of linear and X-shaped oligo（para-phenylene） derivatives functionalized with fluorene ethynylenes 1,3 and 4 were synthesized through sequent Sonogashira coupling and Suzuki-Miyaura reaction in high yield.The electron-donating group-OCH3 and electron-withdrawing counterparts-CF3 were introduced to tune the spectra properties of compounds 3 and 4.The detail investigation of their photophysical properties in solution and film indicated that the introduction of both -OCH3 and -CF3 makes maximum emission distinct red-shift in comparison with parent compound 1,but the latter more prominently.

Novel Bis-β-diketone-type Ligand and Its Copper and Zinc Complexes for Two-photon Biological Imaging

A curcumin derivative ligand,1,7-bis（3-methoxyl-4-oxyethylacetate）phenyl-1,6-heptadiene-3,5-diketone（diethyl acetatecurcumin,abbreviated as HL）,and its Cu（II） and Zn（II） complexes have been synthesized and characterized by elemental analyses,infrared（IR）,1H NMR and molar conductivity.The experimental results show that the resulting complexes bear strong two-photon excited fluorescence（TPEF） in N,N-dimethyformamide solvent,which has been proven to be potentially useful for two-photon microscopy imaging in living cells.In addition,cytotoxicity tests show that the low-micromolar concentrations of metal-ligand complex（ML2） did not cause significant reduction in cell viability over a period of,at least,24 h and should be safe for further biological studies.

Tailor-Made Dynamic Fluorophores:Precise Structures Controlling the Photophysical Properties

Organic fluorophores with dynamic conformations in the excited state have played a significant role in applications of organic functional dyes.Among them,dihydrophenazine-based dynamic fluorophores involving a photoinduced structural planarization process in the excited state exhibited large Stokes shifts and conformation-dependent multicolor emissions.With the developments of synthetic strategies,precise modifications on dihydrophenazinebased scaffolds have successfully afforded a variety of precise molecular structures of varying sizes and compositions,which have delicately modulated their photophysical properties.Herein,this Perspective summarizes the precise modulations of dihydrophenazine-based dynamic fluorophores,including the development of the synthetic methodologies,and tailor-made molecular models to reveal the luminescence−structure relationships.

Synthesis, Crystal Structure and Two-photon Absorption Properties of 4′-(N,N-di(4-hydroxymethyl phenyl) amino)phenyl-2,2′:6′,2''-terpyridine

A novel donor-acceptor （D-A） triphenylamino terpyridine derivative L was facilely synthesized and fully characterized, and its single crystals were obtained and determined by X-ray diffraction analysis. It crystallizes in triclinic, space group P/ with a = 11.760（5）, b =12.516（5）, c = 12.850（5） A, α = 67.141（5）, β= 65.284（5）, γ = 75.876（5）°, Mr = 621.54, F= 1575.6（11） A3, Z= 2, Dc = 1.310 g/cm3,μ = 0.245 mm-1, F（000） = 648, the final R = 0.0671 and wR = 0.1869 for 11328 observed reflections with 1〉 2σ（I）. Linear and nonlinear optical properties of terpyridine derivative L were systematically investigated. The maximum two-photon cross-section of L was 382.5 GM （Goeppert-Mayer）, measured by two-photon excited fluorescence （TPEF） method. This result demonstrates that the increase of intramolecular charge transfer （ICT） leads to enhanced two-photon absorption （2PA）, which could be achieved by introducing additional electron-donor groups to the molecular framework.

Bromine-contained and Modified with Amino Group, D-π-A α-Cyanostilbenzene Derivative：Synthesis, Crystal Structure and Photoluminescence

A novel D-π-A type α-cyanostilbenzene derivative,（Z）-2-（4-aminophenyl）-3-（4-bromophenyl）-acrylonitrile（ABAN）, was designed and synthesized, by introducing an electrondonating amino group and a heavy atom. The structure of ABAN was confirmed by FT-IR, 1H NMR, 13 C NMR spectra and single-crystal X-ray diffraction analysis. The ABAN is of orthorhombic system, space group P212121, with a = 8.6100（14）, b = 9.6923（16）, c = 15.705（3） , Mr = 299.17, V = 1310.6（4） 3, Z = 4, Dc = 1.516 g/cm-3, μ = 3.119 mm-1, F（000） = 600, Rint = 0.038, R（I 〉 2σ（I）） = 0.0276, w R（I 〉 2σ（I）） = 0.0628, R（all data） = 0.0324, wR（all data） = 0.0646, completeness to theta = 25.00 was 99.8% and GOOF = 1.04. In the crystal structure, ABAN molecules were linked with each other through intermolecular C–H···π interactions and N–H···N hydrogen bonds, by which the 1D chain, 2D plane and 3D stacking structures were constructed. The photophysical properties and calculation results confirmed that ABAN possessed an intramolecular charge transfer（ICT） process. ABAN could be applied into the optoelectronic material field due to good solvent-tuned photophysical properties and highly thermal stability.

Synthesis of New Ruthenium(II) Bipyridyl Complexes and Studies on Their Photophysical and Photoelectrochemical Properties

Two new mixed ligand ruthenium(II) complexes, Ru(dcbpy)^(LL)(NCS) 2 [where dcbpy=4,4′ dicarboxyl 2,2′ bipyridine, LL=4,4′ bis( N methyl anilinomethyl) 2,2′ bipyridine (1) or 4 methyl 4′ N methyl anilinomethyl 2,2′ bipyridine (2)], were synthesized, and the photophysical properties of these complexes were studied. The metal to ligand charge transfer (MLCT) transitions of these complexes exhibited solvatochromic effect due to the existence of NCS ligands. The MLCT energies also strongly depend on the pH values of the solutions because of protonation and deprotonation of the carboxyl groups. The p K a values of the ground state, 4 0 for 1 and 3 8 for 2, were obtained from the titration curves. The photoelectrochemical properties of 1 and 2 as sensitizers in sandwich type solar cells have been studied. Complex 1 exhibited better photoelectrochemical behavior than complex 2 as expected. It was proved that the design of mixed ligand complex by introducing electron donating group in one of the ligands should be a promising approach.

Thienothiophene-centered ladder-type π-systems that feature distinct quinoidal π-extension

Quinoidalπ-conjugated structures,a kind of fundamental subunits for organicπ-systems,may produce some intriguing optical,electronic and magnetic properties of polycyclic hydrocarbons(PHs).Herein,we report two thienothiophene-centered ladder-type polycyclic molecules(1 and 2),which possess one quinoidal thienothiophene moiety and two para-quinodimethane(p-QDM)subunits,respectively.As theoretically and experimentally studied,while 1 is a fully closed-shell molecule,2 owns an open-shell structure along with partial contribution of tetraradical state that is induced by the resonance of p-QDM.Moreover,although 2 has a largerπ-conjugated skeleton and open-shell electronic state,it exhibits larger bandgap and blue-shifted absorption.On the other hand,the reversible oxidation activity of 1 enables the preparation of its dication 1^(2+),and the studies on its single-crystal and aromatic structures demonstrate that its two positive charges are delocalized onto the oxygen atoms,thus achieving fullyπ-extended structure and near-infrared absorption.This study not only gains insight into quinoidalπ-subunits,but also provides an important basis for the development of antiaromatic and open-shellπ-electron materials.

Unveiling non-radiative center control in CsPbBr_(3) nanocrystals:A comprehensive comparative analysis of hot injection and ligandassisted reprecipitation approaches

Metal-halide perovskite nanocrystals(NCs)have gained significant attention in the field of optoelectronic and photonic devices due to their promising applications.Despite their exceptional optical properties,the impact of different synthetic strategies on the fundamental nature of NCs,such as nonradiative recombination centers,remains poorly understood.In this study,we investigated the photophysical properties of CsPbBr_(3) NCs synthesized using two distinct methods,hot injection and ligand-assisted reprecipitation,at the individual particle level.We observed different blinking behaviors under specific photoexcitation power densities and proposed,through intensity-lifetime analysis and Monte-Carlo simulations,that these different synthetic strategies can fabricate NCs with similar crystal structures but distinct surface quenchers with varying energy levels,which significantly affected the photo-induced blinking-down and blinking-up behaviors in individual NCs.Our findings indicate a practical and feasible approach for controlling defect engineering in perovskite NCs,with significant implications for their use in optoelectronic and other technological applications.

Anthracene-based Derivatives： Synthesis, Photophysical Properties and Electrochemical Properties

A series of anthracene-based derivatives, namely, 9-（4-phenyl）anthracene（1）, 9-（4-phenylethynyl）- anthracene（2） and 9, 10-bis（phenylethynyl）anthracene（3）, was synthesized by the Suzuki/Sonogashira cross-coupling reactions in good yields. These compounds were fully characterized by X-ray crystallography, thermogravimetric analysis（TGA）, differential scanning calorimetry（DSC）, UV-Vis absorption and fiuorescence（FL） spectroscopy, as well as density functional theory（DFT） calculations. Single-crystal X-ray analysis revealed that the packing structures were influenced by the terminal substitutions. All the compounds exhibited high thermal stability（Td=221---484 ~C） and blue emission with a high quantum yield（~bf =0.20--0.75）. As the number of substituents increased, the decomposition temperatures（Td） of these compounds increased in the following order： 1〈2〈3. Experiments on the photophysical properties revealed that different substituents strongly affected the optical properties. In particular, compound lb with the electron-withdrawing group（--CHO） exhibited a larger Stokes shift（113 nm） than the other compounds. Investigation of the electrochemical properties of these compounds showed that the HOMO-LUMO energy gaps（Egap） decreased obviously as the degree of conjugation increased.

Photophysical properties of the Corrole photosensitizers

The photophysical properties of a series of hydroxyl Corroles, Corrole-F, Corrole-Cl, Corrole-Br, Corrole-I and Corrole-2I, have been investigated by steady-state and time-resolved transient spectroscopy. The absorption spectra show a strong peak around 420 nm corresponding to B band and several weak Q absorption bands between 450 nm and 650 nm, exhibiting much stronger Q band absorption than that of porphyrin. The absorptions of these Corroles increase with the atom weight and the number of halogen atoms. All samples show similar fluorescence characteristics of an emission peak at 650 nm. The fluorescence intensities significantly decrease with the atom weight and the number of halogen atoms. The fluorescence quantum yield of Corrole-I is 0.947%, which is larger than that of Corrole-2I (0.381%). The fluorescence dynamics of the hydroxyl Corroles shows that both the fluorescence lifetime and the intersystem-crossing transition time of these Corroles decrease sharply with the increase of the atom weight and the number of halogen atoms, which may lead to the increase of the triplet state quantum yield. The heavy-atom effect on active oxygen of PDT has also been discussed by the end of this paper.

Synthesis and photophysical properties of porphyrin-phthalocyanine heterodimer linked by piperazine

A porphyrin-phthalocyanine heterodimer linked by piperazine has been synthesized and characterized by spectroscopic methods. UV-visible absorption spectra indicated the presence of weak intramolecular interaction between the two chromophores. Selective excitation of the porphyrin moiety leads to energy transfer process to the phthalocyanine subunit. Furthermore, on the bases of the solvent-dependent fluorescence data, a competing electron transfer reaction is shown to occur in this heterodimer. The efficiency of both photophysical processes depends strongly on solvent polarity and is related to the separation distance of the two chromophores and their relative orientation. The value of ΔG obtained using the Rehm-Weller equation clearly indicates that the heterodimer exists preferably in the “boat form” upon excitation in good agreement with the experimental results of co-occurence of energy and electron transfer process observed for the heterodimer.

Synthesis, Photophysical Properties and Near Infrared Electroluminescence of 1 （4）,8（11）,15（18）,22（25）-Tetra- （methoxy-phenoxy） phthalocyanine

A new soluble phthalocyaine 1 （4）,8（11）, 15（18）,22（25）-tetra-（methoxy-phenoxy）phthalocyanine （MPPc） was synthesized and verified by mass spectrum （MS）, 1H NMR, IR and elemental analysis. The methoxy-phenoxy groups were introduced in order to enhance the solubility of the phthalocyanine. The photophysical and electrolu- minescent properties were investigated. The organic light-emitting diodes （OLEDs） with the structure of ITO/PVK：MPPc（40 nm）/BCP（20 nm）/Alq3（30 nm）/Al were fabricated. Room-temperature near infrared （NIR） electroluminescence （EL） was observed near 891 nm that effectively covered the first optical communication win- dow near 850 nm.