- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Tunable Photophysical Properties of Thiophene Based Chromophores: Conjoined Experimental and Theoretical Investigation
摘要： In this paper we report synthesis and photophysical properties of six novel thiophene derivatives (ThD) with D-π-A structure. The subject of this work are three nitrophenyls (1) BT-Th-NO2 and three benzonitriles (2) BT-Th-CN, substituted at different positions of aromatic ring ((a) ortho-, (b) meta- or (c) para-). Dyes were obtained using simple three-step synthesis and their chemical structures were confirmed by 1H and 13C NMR, IR as well as high resolution mass spectrometry. The influence of positional isomerism on optical properties has been explored experimentally and theoretically. The photophysical properties were investigated using steady-state as well as time-resolved spectroscopy and the obtained results were supported by quantum-chemical calculations. TD-DFT calculations indicated that charge-transfer strength can be correlated with the observed optical properties. In addition, the influence of the acceptor position on photoluminescence spectra, fluorescence quantum yields and emission lifetimes was specified. We show that ThD optical properties can be tuned in wide spectral range by the change made in only single step of synthesis reaction.
关键词： push-pull chromophores,Thiophene derivatives,TD-DFT,quantum yield,charge transfer
更新于2025-11-19 16:46:39
-
Synthesis, characterization and comparative studies of nonlinear optical chromophores with rod-like, Y-shaped and X-shaped configurations
摘要： A series of highly polarizable nonlinear optical (NLO) chromophores ZJ1-4 with three different configurations, including rod-like, Y-shaped and X-shaped configurations, have been synthesized with facile routes and systematically studied. The resulted chromophores exhibited excellent thermal stabilities. The relationship between molecular configuration and NLO activity was analyzed from the theoretical calculation and experiment. The molecular dipole moment of chromophore ZJ4 was enhanced by X-shaped structure with two acceptors. Meanwhile, the tendency of forming anti-parallel interactions could be inhibited by disk-like molecular configuration with larger steric hindrance. ZJ4 exhibits the largest EO activity of 103 pm/V, and both of molecular and material NLO properties are improved for the chromophore ZJ4 with the X-shaped configuration compared with corresponding benchmark chromophore ZJ1 with rod-like molecular structure.
关键词： shape,nonlinear optic,electro-optic,structure-property relationship,chromophores
更新于2025-09-23 15:23:52
-
Effect of the Chirality of Counter Anions on the Vapochromic Behavior of Luminescent Pt(II) Complexes
摘要： New luminescent Pt(II) complexes with the chiral counter anions [PtCl(tpy)](L-Hta) (1-L) and [PtCl(tpy)](DL-Hta) (1-DL; tpy = 2,2’:6’,2’’-terpyridine; L-H2ta = L-tartaric acid; DL-H2ta = racemic tartaric acid) were synthesized and their vapochromic behavior was evaluated. Single crystal X-ray analysis revealed that the stacked square-planar Pt(II) molecules in anhydrous 1-DL formed a one-dimensional columnar structure with weak intermolecular Pt···Pt interactions, while in anhydrous 1-L the Pt(II) molecules were dimerized with Pt…Pt interactions to form a zig-zag stacked column. These differences were attributed to the different hydrogen bonding in the DL- and L-Hta? ions. The dihydrates of 1-DL and 1-L displayed near-identical crystal structures with comparable emission spectra derived from 3π–π* ligand emission. Both dihydrates exhibited MeOH-vapor-induced dehydration to form the anhydrous complexes. These presented broad 3MMLCT emission (549 and 565 nm, respectively), affected by the degree of intermolecular Pt···Pt interactions.
关键词： luminescence,chromophores,platinum
更新于2025-09-23 15:23:52
-
Prediction of Second-Order Nonlinear Optical Properties of D–π–A Compounds Containing Novel Fluorene Derivatives: A Promising Route to Giant Hyperpolarizabilities
摘要： Herein, ?rst attempt has been made to utilize ?uorene-based dye-sensitized solar cell (DSSCs) dye JK-201 as potential nonlinear optical (NLO) material and for the theoretical designing of novel NLO chromophores JK-D1–JK-D12. DFT/TDDFT calculations were performed to compute the effect of p-linkers and acceptors-steered modulation on electronic, photophysical and NLO properties of JK-201 and JK-D1–JK-D12. Results illustrate that computed kmax (484.74 nm) and experimentally calculated kmax (481 nm) of JK-201 was found in good agreement. Maximum red shifted absorption spectrum was observed in JK-D12 with 599.38 nm. JK-D1–JK-D12 showed narrow energy gap and broader absorption spectrum as compared to JK-201. NBO analysis con?rmed the formation of charge separation state due to robust range of electrons/charge transfer from donor to acceptor via p-bridge. Giant NLO response was observed in all compounds. Particularly, JK-D12 displayed surprisingly large hai and btot computed 1376.74 (a.u.) and 405,731.84 (a.u.) respectively. Although literature is ?ooded with D–p–A compounds investigated for their DSSCs properties, but research reports on their NLO properties and utilization as NLO materials are completely deserted. Our research will open new horizons to explore DSSCs materials for NLO applications. This theoretical framework also exposed that ?uorene-substituted chromophores are excellent NLO candidates for modern hi-tech applications.
关键词： D–p–A organic chromophores,Acceptor units,Molecular modeling,Density functional theory,NLO response properties,p-Conjugated linkers
更新于2025-09-23 15:22:29
-
Assessment of functionals for TDDFT calculations of one- and two-photon absorption properties of neutral and anionic fluorescent proteins chromophores
摘要： Performance of DFT functionals with different percentage of exact Hartree-Fock exchange energy (EX) is assessed for recovery of the CC2 reference one- (OPA) and two-photon absorption (TPA) spectra of fluorescent proteins chromophores in vacuo. The investigated DFT functionals, together with their EX contributions are: BLYP (0%), B3LYP (20%), B1LYP (25%), BHandHLYP (50%) and CAM-B3LYP (19% at short range and 65% at long range). Our test set consists of anionic and neutral chromophores as naturally occuring in the fluorescent proteins. For the first time, we compare TDDFT and CC2 methods for higher excited states, than the S1 state, exhibiting relatively large TPA intensity. Our TDDFT results for neutral chromophores reveal an increase of excitation energies as well as TPA and OPA intensities errors, compared to CC2-derived results, as the DFT functional contains less exact exchange. The long-range-corrected CAM-B3LYP functional performs the best, closely followed by BHandHLYP, while BLYP usually significantly underestimates all investigated spectral properties, hence being the worst in reproducing the reference CC2 results. The hybrid B3LYP and B1LYP functionals can be roughly placed in between. We propose that TDDFT may underestimate the TPA intensities for neutral chromophores of fluorescent proteins due to underestimated oscillator strengths between some excited states. In case of anionic chromophores, we find that B3LYP and B1LYP functionals overcome others in terms of reproducing CC2 excitation energies. On the other hand, however, TPA intensity is usually significantly underestimated and in this respect CAM-B3LYP functional seems to be again superior. In contrast to the case of neutral chromophores, it seems that large magnitude of excited-state dipole moment or change in dipole moment upon excitation may be the driving force behind high TPA transition moments.
关键词： fluorescent proteins chromophores,one-photon absorption,DFT functionals,two-photon absorption,TDDFT,CC2
更新于2025-09-23 15:21:21
-
Ancient Family of Retinal Proteins Brought to Light “Sight-Unseen”
摘要： Rhodopsins are an ancient class of light-sensing membrane proteins that bind retinylidene chromophores in order to form pigments that absorb visible light. Light absorption triggers isomerization of the chromophore, which is bound covalently within the transmembrane core of the protein, an event that drives protein conformational changes. Type-1 rhodopsins are also known as microbial rhodopsins, which include the well-known light-driven protein pump bacteriorhodopsin found in archeabacteria. Type-2 rhodopsins, or animal rhodopsins, include the sensory rhodopsins used as visual pigments found in most animals, including humans. Both Type-1 and -2 rhodopsins share a canonical seven-transmembrane helical polytopic structure with their amino terminal tails projecting to the topological outside of the cell membrane. Rhodopsins harness light energy to perform a vast array of functions, including pumping ions, gating channel activity, activating coupled enzyme systems, and transducing light sensation in vision. Pushkarev et al. have now reported the discovery of an entirely new group of microbial rhodopsins, opening up the potential for the elucidation of an extensive new class of rhodopsins that they term “heliorhodopsins.”
关键词： heliorhodopsins,retinylidene chromophores,light-sensing,membrane proteins,rhodopsins
更新于2025-09-23 15:21:21
-
Highly Polarized Coumarin Derivatives Revisited: Solvent-controlled Competition Between Proton Coupled Electron Transfer and Twisted Intramolecular Electron Transfer
摘要： Linking a polarized coumarin unit with an aromatic substituent via an amide bridge results in weak electronic coupling affecting the intramolecular electron transfer (ET) process. As a result of this, interesting solvent-dependent photophysical properties can be observed. In polar solvents, electron transfer in coumarin derivatives of this type induces a mutual twist of electron-donating and electron-accepting molecular units (TICT process) that opens radiationless decay processes (internal conversion). In the dyad with the strongest intramolecular hydrogen bond, the planar form is stabilized so twisting can only occur in highly polar solvents, whereas fast proton coupled electron transfer (PCET process) occurs in non-polar n-alkanes. The kPCET rate constant decreases linearly with the fluorescence maximum energy in different solvents. This observation is explained in terms of competition between electron and proton transfer from a highly polarized (~15 D) and fluorescent locally-excited (1LE) state to a much less polarized (~4 D) charge-transfer (1CT) state, a unique occurrence. Photophysical measurements performed for a family of related coumarin dyads together with results of quantum-chemical computations give insight into the mechanism of the ET process which is followed by either a TICT or PCET process. Our results reveal that dielectric solvation of the excited state slows down the PCET process, even in non-polar solvents.
关键词： coumarins,donor-acceptor systems,absorption,fluorescence,chromophores
更新于2025-09-23 15:21:01
-
Chromophores in cellulosics, XVIII. Degradation of the cellulosic key chromophore 5,8-dihydroxy-[1,4]-naphthoquinone under conditions of chlorine dioxide pulp bleaching: a combined experimental and theoretical study
摘要： DHNQ is one of the key chromophores occurring in all types of aged cellulosics. This study investigates the degradation of DHNQ by chlorine dioxide at moderately acidic (pH 3) conditions, corresponding to the conditions of industrial bleaching ("D stage"). The degradation involves three major pathways. As initial reaction, a hydrogen transfer from DHNQ to chlorine dioxide via a PCET mechanism occurs to form a radical DHNQ(cid:2) and chlorous acid. DHNQ(cid:2) is then attacked by water to give a pentahydroxynaphthalene radical PHN(cid:2) that is stabilized by strong delocalization of the non-paired electron into its aromatic ring. PHN(cid:2) immediately disproportionates to give the observable intermediate 1,2,4,5,8-pentahydroxynapththalene (I), which was comprehensively con?rmed by NMR and MS (path A). In the presence of excess ClO2, I is immediately further oxidized into acetic acid, glycolic acid, oxalic acid and CO2 as the ?nal, stable, and non-colored products (path C). In the absence of excess ClO2, elimination of water from I regenerates DHNQ (path B), so that at roughly equimolar DHNQ/ClO2 ratios ClO2 is fully consumed while a major part of DHNQ is recovered. To avoid such DHNQ "recycling" under ClO2 consumption—and to completely degrade DHNQ to colorless degradation products instead—ClO2 must be applied in at least ?vefold molar excess relative to DHNQ.
关键词： Density functional theory (DFT),Ab initio calculations,Yellowing,Cellulose,Brightness,Chromophores,5,8-dihydroxy-[1,4]-naphthoquinone,Chlorine dioxide,Brightness reversion,Pulp bleaching
更新于2025-09-23 15:21:01
-
Chromophores with side isolate groups and applications in improving the poling efficiency of second non-linear optical (NLO) materials
摘要： In this paper, alkyl groups with different lengths are introduced to the two-dimensional spindle-type chromophores as the steric isolators to improve the poling efficiency and long term stability of the poled polymers for second-order nonlinear optical materials. The structure and thermal properties of alkyl functionalized chromophores are characterized by the 1H-NMR, FT-IR, UV-Vis, DSC, TGA, et al. The chromophores with different alkyl groups present extremely similar maximum absorbance wavelength (480nm), which means they have very similar first-order hyperpolarizability. Guest-host polymer doped with chromophores has been prepared. Those materials display different glass transition temperatures and good thermal stability. According to the electro-optic coefficients studies and poling efficiency results, chromophores with longer alkyl side chain groups exhibit better poling efficiency and larger electro-optic coefficients. Especially for the chromophores with octyl group, the poling efficiency increases up to 3 times compared to the reference chromophore 2-(3-{2,5-Phenylmethanol-4-[4-(dimethylamino)styryl]-styryl-5,5-dimethylcyclohex-2-enylidene)malononitrile (STC), while the corresponding electro-optic coefficient of the poled polymers increases up to 4 times, indicating a significant effect of the isolate groups on improving the poling efficiency.
关键词： Chromophores,Electro-optical (EO),Nonlinear optics,Poling efficiency
更新于2025-09-23 15:21:01
-
Electrically controlled white laser emission through liquid crystal/polymer multiphases
摘要： White lasers are becoming increasingly relevant in various fields since they exhibit unprecedented properties in terms of beam brightness and intensity modulation. Here we introduce a white laser based on a polymer matrix encompassing liquid crystals and multiple organic chromophores in a multifunctional phase-separation system. The separation of the hydrophilic matrix and the hydrophobic liquid crystals leads to the formation of a complex optically active layer, featuring lasing emission tuneable from blue to red. White laser emission is found with an optical excitation threshold of approximately 12 mJ/cm2. Importantly, an external electric field can be used to control the device emission intensity. White lasers with low-voltage (≤10 V) controllable emission might pave the way for a new generation of broadband light sources for analytical, computational, and communication applications.
关键词： polymer matrix,electrically controlled,liquid crystal,organic chromophores,white laser
更新于2025-09-23 15:19:57