Design Strategy of Infrared 4-Hydroxybenzylidene-imidazolinone-Type Chromophores based on Intramolecular Charge Transfer:a Theoretical Perspective

Partial genetically encoded 4-hy-droxybenzylidene-imidazolinone(HBI)-type chromophores are new promising fluorescent probes,which are suitable for imaging and detection of living cells.How-ever,the lack of infrared chro-mophores hinders the develop-ment seriously.Here more than 30 HBI-type chromophores with reg-ular structure modifications were employed and typical spectral redshift change laws and mechanisms were investigated by quantum methods.Results show that both one-photon spectrum(OPS,absorption/emission)and two-photon absorption(TPA)can achieve large redshift via either extending conjugated lengths of frag-3 or enlarging conjugated areas of frag-1 of HBI skeleton.Spectral redshifts of all chromophores are highly related to intramolecular charge transfer(ICT),but neutral ones are closely related to the total ICT or electron-accept-ing-numbers of frag-3,and the high correlative factor of anions is the aromaticity of frag-2 bridge.The frag-2 bridge with high aromaticity can open a reverse charge transfer channel in anion relative to neutral,obtaining significant redshift.Based on analysis,a new 6-hydroxyl-naphthalene-imidazolinone(HNI)series,which have larger conjugated area in frag-1,are pre-dicted.The OPS and TPA of anionic HNI ones acquire about 76−96 nm and 119−146 nm red-shift relative to traditional HBI series respectively as a whole.The longest emission of anionic HNI-4 realizes more 244 nm redshift relative to HBI-1.Our work clarifies worthy spectral reg-ularities and redshift mechanisms of HBI-type chromophores and provides valuable design strategy for infrared chromophores synthesis in experiment.

Optimization of the Assembly Efficiency for Lidamycin Chromophore Bound to its Apoprotein:A Case Study using Orthogonal Array

Objective Lidamycin （LDM） can be dissociated to an apoprotein （LDP） and an active enediyne chromophore （AE）. The detached AE can reassemble with its LDP-containing fusion protein to endow the latter with potent antitumor activity. However, the reassembly of AE with LDP is affected by several factors. Our aim was to optimize the assembly efficiency of the AE with a LDP-containing fusion protein and investigate the influence of several factors on the assembly efficacy. Methods A method based on RP-HPLC was developed to analyze the assembly rate, and an orthogonal experimental design L9 （3^4） was used to investigate the effects of temperature, assembly time, pH and molecular ratio of LDP-containing fusion protein to AE on the assembly rate. Furthermore, the determined optimum conditions for the assembly rate of the LDP-containing fusion protein with AE were applied and evaluated. Results A calibration curve based on the LDM micromolar concentration against the peak-area of AE by HPLC was obtained. The order in which individual factors in the orthogonal experiment affected the assembly rate were temperature〉time〉pH〉molar ratio of AE to protein and all were statistically significant （P〈0.01）. The optimal assembly conditions were temperature at 10 ℃, time of 12 h, pH 7.0, and the molar ratio of AE： protein of 5：1. The assembly rate of AE with a LDP-containing fusion protein was improved by 23% after condition optimization. Conclusion The assembly rate of chromophore of lidamycin with its LDP-containing fusion protein was improved after condition optimization by orthogonal design, and the optimal conditions described herein should prove useful for the development of this type of LDP-containing fusion protein.

Synthesis and Non-linear Optical(NLO) Properties of a Series of Alkoxysilane Derivative Chromophores

1 Introduction Nonlinear optical materials（NLO） have drawn a great intrest of some scholars and scientists in the last dacades because of their tremendous potential application in optoelectronic. The fabrication of efficient optoelectron devices is a challenging task because such systems need to meet the stringentable requirements for high optical quality and large and sustainable electro-optical（EO） response. In pursuit of NLO materials with excellent optoelectronic property,

Subunit composition and chromophore content of R－phycocyanin and allophycocyanin from Porphyra haitanensis

R-phycocyanin (RPC) of Porphyra haitanensis (T. J. Chang et B. F. Zheng )' was chromatographed on Bio-Rex 70 column with urea solution (pH 3. 0) as an eluent, and a and β two subunits were isolated.Their molecular weights were determined on SDS-PAGE at 18 400 and 20 500, respetively,while those of a and β subunits of allophycocyanin (APC) at 18 800 and 19 700, respectively,and those of RPC and APC were at 117 000 and 122 000,respectively.Both the molar ratio of a and β subests of RPC and APC were 1:1, and the subunit composition was confirmed to be (αβ )3.It was ascertained that in RPC αsubunit contains one chromophore phycocyanobilin (PCB) and β subunit has one chromophore PCB and one phycoerythrobilin (PEB), while in APC both α and βsubunits contain one PCB.

Nonlinear optical properties of novel H-shaped chromophores

Novel and effective H-shaped chromophores were doped into polymethyl methacrylate （PMMA） to form guest-host polymer thin films. The measurement results of Maker fringe method show that the polymer thin films containing the H-shaped chromophores as a guest exhibit high second harmonic coefficients （d33） compared with other two-dimensional chromophores.

Synthesis and Nonlinear Optical Property of a Series of New Chromophores Containing Furan Ring as the Only Conjugation Bridge

This paper reports the synthesis and the nonlinear optical property of a series of new chromophores which contain furan ring as the only conjugation bridge for the first time. They are characterized by UV-VIS, FT-IR, H-1 NMR, MS and elemental analysis. Their dipole moment and the first-order molecular hyperpolarizability (beta) are calculated and compared with those or the analogues containing either benzene or thiophene as file conjugation bridge.

Synthesis,Characterization,and Linear and Nonlinear Optical Properties of Phenylene-vinylene Based Chromophores for Singlet Oxygen Generation

A series of symmetrical and unsymmetrical phenylene-vinylene （PV） based chro- mophores with the molecular configuration of donor-π-donor （D-g-D） were prepared and characterized. Iodine was first introduced into the Jr-conjugation backbone of the PV based chromophores in order to study the heavy atom effect on their linear absorption, two-photon absorption （TPA） properties, as well as singlet oxygen generation properties. TPA cross-sections of these chromophores were investigated by using the two-photon excited fluorescence method. The unsymmetrical chromophores were found to have larger TPA cross-section values compared to their symmetrical counterparts. For one of the unsymmetrical chromophores with the iodine incorporation, a large TPA cross section value with quenched emission was found. The decreased fluorescence quantum yield of a molecule can be ascribed to the increased intersystem crossing, which is favorable for enhancing the singlet oxygen generation. Therefore, the unsymmetrical PV based chromophores with heavy atom incorporation are promising singlet oxygen sensitizers for the photodynamic therapy application.

Theoretical Studies on the First Hyperpolarizabilities of One-dimensional Donor-bridge-acceptor Chromophores

The ground-state dipole moments and second-order nonlinear optical （NLO） properties of a series of one-dimensional （1D） chromophores with donor-bridge-acceptor （D-B-A） structures have been investigated by using the second-order MФller-Plesset （MP2） and density functional theory （DFT） methods with the basis set of 6-31＋G（d）. According to the calculated results, the relationship between the molecular static first hyperpolarizability （βμ） and the directions of electron transition has been summarized. In terms of the sign of βμ, these 1D organic chromophores were classified into two categories： type Ⅰ with negative βμ and type Ⅱ bearing positive βμ. The analyses show that the remarkable difference of the first hyperpolarizabilities between Ⅰ and Ⅱ chromophores is associated mainly with the electrostatic interaction between terminal groups and the transport electrons in excited states. Moreover, different from the popular viewpoint, the obtained results also show that most of this series of 1D D-B-A molecules are more charge-separated in the ground states than in the excited states. As a whole, this theoretical investigation, to some extent, can be considered as a useful reference in designing the NLO chromophores with large first hyperpolarizabilities.

NONLINEAR OPTICAL PROPERTIES OF X-TYPE CHROMOPHORES AND THEIR DOPED FILMS

Two X-type chromophores, 2-[4-(4,5-di(4-nitrophenyl) imidazolyl) phenyl]-4,5-di(4-methoxyphenyl)-imidazole (DNPIPDMOPI), 2-[4-(4,5-di(4-nitrophenyl)-imidazolyl) phenyl]-4,5-di(4-aminophenyl)-imidazole (DNPIPDAPI), were synthesized and characterized. The results show that they possess good nonlinearity, considerable blue-shifted absorption (385 nm and 379 nm in THF) and high decomposition temperature (377 'C and 405 'C). These mean that the X-type chromophores possess a rather good nonlinearity-transparency-thermal stability trade-off. The multi-step corona-poling technique at elevated temperature and in-situ SHG measurements were used to obtain and evaluate the poled films of these chromophores doped in PMMA. The largest SHG signals appeared at 110-120°C, which are 12.5 pm/V and 16.7 pm/V respectively. The dependence of poling induced orientation stability on temperature was measured by depoling experiments and the results indicate that the poling-induced orientation of the films is stable at about 100°C. Theoretic analyses imply that better orientation stability arises from the X-type structure of chromophore. The X-type chromophore has two crossed intramolecular CT, both β xxx and β xyy can contribute to the second-order susceptibility, and the ratio of the tensorial components (γ= β xyy /β xxx ) is about 1/3, so the orientation decay of the films induced by rising temperature will provide a certain compensation for the contribution of β xyy of chromophores.

Theoretical Studies on the First Hyperpolarizabilities of One-dimensional Donor-bridge-acceptor Chromophores and New Applications of BLA in Determining Molecular First Hyperpolarizabilities

We present a quantum-chemical analysis of the relationship between the bond length alteration （BLA） and the static first hyperpolarizability of a series of one-dimensional （1D） chromophores with donor-bridge-acceptor （D-B-A） structures. The calculated results show that the parameter BLA can be considered as an indicator to evaluate the molecular first hyper- polarizability. Along the direction of molecular ground-state dipole moments, the evolutions of BLA can be classified into three categories： the first is a non-monotonic line, which represents most chromophores; the second is monotonic increasing; and the third, contrarily, is monotonic decreasing. On the whole, the first hyperpolarizabilities of these studied chromophores are the monotonic functions of BLA along the direction of dipole moments. Therefore, the first hyperpolarizability of these 1D chromophores can be preliminarily evaluated in terms of the development of BLA without a rigorous computation. In other words, one can roughly estimate the relative magnitude of the first hyperpolarizability according to the optimized geometry.

Synthesis and characterization of multifunctional copolyimide incorporating triarylamine and NLO chromophore in backbone

Presents the synthesis of Copolyimide containing triarylamine and NLO chromophore in backbone by azo coupling of 4 nitrobenzenediazonium tetrafloroborate to copoly(amic acid) in organic solvent and characterized by IR and UV Vis spectra, which had high glass transition temperatrue and big second order nonlinear optical coefficient  x (2) .

π-conjugated chromophore functionalized high-nuclearity titanium-oxo clusters containing structural unit of anatase for photocatalytic selective oxidation of sulfides

N-doping has significant influence in manipulating the properties of TiO_(2),and this has stimulated the development of N-donor-functionalized titanium-oxo clusters(TOCs)as molecular models to study the structure-property relationship.However,the structural type and photoresponsive application are still limited for such TOCs,especially regarding the high-nuclearity TOCs that contain structure unit of TiO_(2)for photocatalysis.Herein,we showed the synthesis of a series of high-nuclearity TOCs 1-3 compounds usingπ-conjugated 1,10-phenanthroline(phen)as chromophore and N-donor functional ligand.Compound 1 features cocrystal structure composed of one[Ti_(26)]~(2+)and half[Ti_(22)]~(2+),which renders it as the first cocrystallized TOC containing two positively charged species and phen-functionalized TOC showing the highest nuclearity up to 37 Ti centers.By adjusting the synthetic conditions,the individual{Ti_(22)}and{Ti_(26)}clusters can also be isolated as Compounds 2 and 3,respectively.The core structure of{Ti_(22)}is mainly constructed from four lacunary{Ti_(4)}derived from pentagonal{Ti(Ti)_5}unit,while{Ti_(26)}is built from four complete{Ti(Ti)_5}unit.Notably,a{Ti_8O_(14)}structure unit of anatase TiO_(2)can be identified in{Ti_(26)}.Based on the unique structural features and proper photophysical and photochemical properties of Compounds 1-3,they are applied for photocatalytic sulfoxidation.Owing to the presence of anatase structure unit in{Ti_(26)}and the synergistic effect from{Ti_(22)}and{Ti_(26)},the catalytic performance presents in the order of Compound 1>Compound 3>Compound 2.This work provides excellent models to understand the structureproperty relationship from the perspective of cocrystallization and Ti-O binding model and will further promote the application of TOCs as functional catalysts for organic transformation.

Feasible Synthesis of N,O-Bidentate Difluoroboron Chromophores through Direct Functionalization of Quinoxalin-2(1H)-ones with Ketones in One Shot

Organic difluoroboron complexes are a kind of potential platforms for a wide range of applications owing to their excellent photophysical properties.Herein,we have explored a simple and direct synthesis methodology for a library of N,O-bidentate difluoroboron complexes from quinoxalin-2(1H)-ones and ketones in one shot.The photophysical properties of the generated complexes were evaluated and the application potential of these compounds on subcellular imaging was also explored.

Triphenylamine-based highly active two-photon absorbing chromophores with push-pull systems

Two triphenylamine-based star-type push-pull chromophores(T1, T2) were designed and synthesized.Triphenylamine serves as the central core and acts as an electron-donating group surrounded by electronwithdrawing pentafluorobenzene or N,N-dimethyl substituted tetrafluorobenzene, which are connected by ethylene bridges. Single-crystal X-ray diffraction confirmed the structures and molecular arrangement of two chromophores. The systematic photophysical research of T1 and T2 absorption characteristics was carried out to gain a better understanding of how structure-property relationships affect the observed nonlinear optical absorption phenomenon. Complementary calculations based on density functional theory(DFT) further confirmed the experimental results. Both chromophores exhibited excellent two-photon absorption(TPA) properties in CH_(2)Cl_(2). Notably, T2 has more remarkable nonlinear optical absorption effects with the TPA cross-section up to 4.24 × 10~7GM. By adjusting the electronic structures of the chromophores through introducing pentafluorobenzene or N,N-dimethyl as functional groups with different electron-donating or withdrawing behaviors, the TPA performance of the small organic molecule could be greatly enhanced. These molecular structures with push-pull systems were excellent candidates for different two-photon applications.

SECOND-ORDER NONLINEAR OPTICAL HYPERBRANCHED POLYMER CONTAINING ISOLATION CHROMOPHORE MOIETIES DERIVED FROM BOTH “H”-TYPE AND STAR-TYPE CHROMOPHORES

An NLO hyperbranched polymer （HP1） derived from both ＂H＂-type and star-type chromophores was synthesized successfully for the first time with high yield via one-pot ＂A2 ＋ B3＂ Suzuki polymerization reaction. Isolation chromophore was also introduced to further improve its performance. Although under the test conditions, the films of HP1 could not be poled completely, it still demonstrated satisfactory macroscopic NLO effect with the second harmonic generation （SHG） coefficient d33 value of 36 pm/V.

Synthesis,structure and nonlinear optical properties of two novel two-photon absorption chromophores

Two triphenylamine-based derivatives that can be used as two-photon absorption chromophore,tris{4-[4-(3-trifluoromethyl-3-oxopanoyl)]phenyl}amine (1) and tris{4-[4-(3-phenyl-3-oxopanoyl)] phenyl} amine (2) were successfully synthesized and fully characterized by elemental analysis,IR,1H NMR and MS. The single crystal X-ray diffraction analysis showed that the molecules possess D-(π-A)3 structures. One-and two-photon absorption and fluorescence in various solvents were experimentally investigated. A data recording experiment proved the potential application of these chromophores.

Effects of chromophore concentration and film thickness on thermo-optic properties of electro-optic fluorinated polyimide films

Electro-optic （EO） effect and thermo-optic （TO） effect are jointly considered on the basis of field-induced and temperature-affected perturbations of the operating point in waveguide components. TO coefficients of EO fluorinated polyimide films with side-chain azobenzene chromophore were measured by attenuated- total-reflection （ATR） technique at different temperatures with TE- and TM-polarized lights, respectively. It is found that the absolute values of TO coefficients increase with the increments of both chromophore concentration and film thickness, but the polarization dependence of TO coefficients increases with the increment of chromophore concentration and decreases with the increment of film thickness.

Theoretical studies of vibrationally resolved absorption and emission spectra: From a single chromophore to multichromophoric oligomers/aggregates

Absorption and photoluminescence spectroscopies are useful tools to study the photo-physical properties of materials. The theoretical methods for calculation of the spectra of molecules/supermolecules and aggregates, whose structures can differ significantly, are reviewed from the viewpoint of computational efficiency. Several model compounds/multimers are taken as examples for the spectral calculations. The numerical results achieve a satisfactory agreement between the theory and experiment.

DFT study on second-order nonlinear optical properties of Pt (Ⅱ) complexes with different chromophores

DFT B3LYP/LANL2DZ method was employed to calculate electron properties and the second-order nonlinear optical(NLO) respond of platinum(Ⅱ) complexes which have been synthesized by Weinstein group.4,7-diphenyl-1,10-phenanthroline shows the ability to push electron in these complexes.Metal Pt plays a balancing charge role.Comparing complex 1b-6b with complex a,the βvec value of complex 1b-5b is larger than one of complex a,while the βvec value of complex 6b is smaller than one of com-plex a.In these seven complexes,the βvec values of complexes increase with decreasing of the energy difference between HOMO and LUMO.Moreover,the electron transfers from deeper layer occupied orbitals to empty orbitals have a distinct contribution to second-order NLO coefficient.