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BODIPY chromophore with pyrene moieties was designed and synthesized successfully in the present paper. Optical results demonstrate that the pyrene-terminated dye 3 presents a bigger Stokes shift and slightly smaller fluorescence quantum yield in the red region than BODIPY dye 1 bearing no substituent at 2,6-positions. Dye 3 possesses absorption and emission maximum at 530 and 585 nm in THF solution, respectively. With the addition of different water volume fractions, the gradually bathochromic shifts are observed in the absorption and emission spectra, simultaneously. Under UV irradiation, the corresponding emission images of solutions/aggregates are visual, showing the aggregation-caused quenching effect of orange fluorescence. In addition, theoretic computational studies on related pyrene decorated chiral BODIPY compounds have also been carried out. [ABSTRACT FROM AUTHOR]

The article discusses the preparation of metal-free corrin derivatives via A/B ring closure. Topics include how the goal for the synthesis of metal-free corrin ligands was achieved in 1968 in the heptamethyl series through adaptation of the sulfide contraction methodology, some ligand properties of synthetic corrin complexes, and methods for the introduction of Me groups in the meso-positions of the corrin chromophore.

Pseudo-mauveine picrate and a synthetic derivative of mauveine, 3-phenylamino-5-(2-methylphenyl)-7-amino-8-methylphenazinium picrate, have been prepared via their leuco-bases and their crystal structures determined. Time-dependent density functional theory gives a good match for the calculated and measured UV-Vis spectra. [ABSTRACT FROM AUTHOR]

Triptycenes spontaneously assemble into two-dimensional networks in which long-range charge transport is facilitated by the extensive electronic coupling through the triptycene framework (intramolecularly) and by cofacial π-stacking (intermolecularly). While designing and synthesizing next-generation triptycenes containing polyaromatic chromophores, the electronic coupling amongst the chromophores was observed to be highly dependent on the nature and position of the substituents. Herein, we demonstrate using hexaalkoxytriptycenes that the electronic coupling amongst the chromophores is switched on and off by a simple repositioning of the substituents, which alters the nodal arrangement of the HOMOs of the individual chromophores. A visual inspection of the HOMOs can thus provide a ready evaluation of the electronic coupling in polychromophoric molecules/assemblies, and will serve as an important tool for the rational design of modern charge-transport materials. [ABSTRACT FROM AUTHOR]

The cocrystallization of a weakly luminescent platinum complex [Pt(btpy)(PPh3)Cl] (1) (Hbtpy=2-(2- benzothienyl)pyridine; emission quantum yield Φem=0.03) with fluorinated bromo- and iodoarenes C6F6-nXn (X=Br, I; n=1, 2) results in the formation of efficient halogen-bonding (XB) interactions Pt-Cl...X-R. An up to 22-fold enhancement (Φem=0.65) in the luminescence intensity of the cocrystallized compound is detected, without a substantial change of the emission energy. Based on crystallographic, photophysical, and theoretical investigations, the contribution of the XB donors C6F6-nXn to the amplification of luminescence intensity is attributed to the enhancement of spin-orbit coupling through the heavy-atom effect, and simultaneously to the suppression of the nonradiative relaxation pathways by increasing the rigidity of the chromophore center. [ABSTRACT FROM AUTHOR]

Introducing appropriate artificial components into natural biological systems could enrich the original functionality. To expand the available wavelength range of photosynthetic bacterial light-harvesting complex 2 (LH2 from Rhodopseudomonas acidophila 10050), artificial fluorescent dye (Alexa Fluor 647: A647) was covalently attached to N- and C-terminal Lys residues in LH2 α-polypeptides with a molar ratio of A647/LH2 ~ 9/1. Fluorescence and transient absorption spectroscopies revealed that intracomplex energy transfer from A647 to intrinsic chromophores of LH2 (B850) occurs in a multiexponential manner, with time constants varying from 440 fs to 23 ps through direct and B800-mediated indirect pathways. Kinetic analyses suggested that B800 chromophores mediate faster energy transfer, and the mechanism was interpretable in terms of Förster theory. This study demonstrates that a simple attachment of external chromophores with a flexible linkage can enhance the light harvesting activity of LH2 without affecting inherent functions of energy transfer, and can achieve energy transfer in the subpicosecond range. Addition of external chromophores, thus, represents a useful methodology for construction of advanced hybrid light-harvesting systems that afford solar energy in the broad spectrum. [ABSTRACT FROM AUTHOR]

Organic dyes containing trifluoromethylated-pyrazolo[3, 4-b]quinoline were synthesized by using condensation reaction between substituted pyrazolo-4-formaldehyde and aryl amines in moderate yields. Quantum calculation, electrochemical, photophysical, and electroluminescent properties were discussed in detail. Electron-withdrawing groups at 6-position of dyes stabilized the LUMO energy levels significantly resulting in red-shifted absorption/emission spectra. Addition of electron-donating group destabilized the HOMO strongly and the LUMO energy levels slightly resulting in red-shifted absorption maxima, but in blue-shifted emission maxima. Experimental and quantum calculation results are presented here to explain this unusual phenomenon. A linear relationship of dipole moments versus Stokes shifts is obtained for these fluorophores, where the increase of dipole moment is accompanied by a decrease in Stokes shift. Organic light-emitting diodes based on selected dyes showed emission at 456 nm, maximum external quantum efficiency at 1.43%, and current efficiency at 1.95 cd/A. [ABSTRACT FROM AUTHOR]

Azadioxatriangulenium (ADOTA) is a fluorescent triangulenium dye with a long fluorescence lifetime, highly polarized transitions and emission in the red part of the visible spectrum. These properties make the chromophore suited for application in fluorescence polarization/anisotropy assays. To be useful for these applications, reactive forms of the dyes must be available in significant quantities. Here, the synthesis and photophysical properties of amine-reactive N-hydroxysuccinimide (NHS) esters and a thiol-reactive maleimide derivative of ADOTA are reported. The synthesis involves two steps of nucleophilic bridge-forming reactions starting from tris(2,6-dimethoxyphenyl)methylium tetrafluoroborate, which can readily be prepared on a 100 g scale. In the third and final step the reactive NHS or maleimide groups are formed. The beneficial photophysical properties of the ADOTA chromophore are maintained in these derivatives, and we conclude that these systems are ideal to study protein motion and protein-protein interactions for systems of up to 1000 kDa. [ABSTRACT FROM AUTHOR]

• Two new Y-shaped ferrocenyl imidazole aldehyde chromophores 1 and 2 have been synthesized and spectroscopically characterized. • Chromophores 1 and 2 show positive solvatochromism due to the higher dipole moment and polarizability in the excited state. • The n -octyl substitution in 2 prevents the anti-parallel alignment in bulk, results high SHG efficiencies. • The experimental results were validated with DFT and TD-DFT calculations using B3LYP, CAM-B3LYP and LC-BLYP with 6–31+ G * * basis set. Two new Y-shaped ferrocene (Fc) conjugated imidazole (IM) aldehyde [(D-π)2-IM-π-A] type chromophores [(Fc-CH=CH) 2 -IM-R-C 6 H 4 -CHO] {R= H (1); C 8 H 17 (2)} have been synthesized and characterized with the aid of analytical and spectroscopic techniques [FT-IR, ESI-Mass, 1H and 13C NMR]. The thermal stability of the chromophores 1 and 2 were investigated using thermogravimetric analysis (TGA), and the chromophores were stable up to 160 ᵒC. The solvatochromic studies of the chromophores 1 and 2 show a positive solvatochromism due to the more polarizable and greater stabilization in the excited state than ground state, when solvent polarity was increased from non-polar to polar. The redox behavior of the chromophores were determined by cyclic voltammetry, and the experimentally observed HOMO and LUMO energy levels were good agreement with the DFT. The second harmonic generation efficiencies (SHG) were investigated by the Kurtz-Perry powder technique using potassium dihydrogen phosphate (KDP) as a standard. The SHG efficiencies of the chromophore 2 is 2.5 times greater than that of the chromophore 1 , because of the presence of n -octyl group which reduces the anti-parallel alignments in molecular packing of the chromophore 2. In addition, the dipole moment (μ) and hyperpolarizability (β 0) were calculated using different functionals (B3LYP, CAM-B3LYP and LC-BLYP), and the B3LYP-hybrid functional is overestimated when compared with long-range CAM-B3LYP and LC-BLYP functionals, because of the incorrected long-range charge transfer behaviour between donor and acceptor in the d-π-A systems. The chromophore 2 shows higher β 0 values in all the different functionals than the 1 , due to the presence of the n -octyl group, which restricts the molecular mobility and makes effective charge transfer process of the chromophore 2. The theoretically observed results followed the same trend as experimental results. The enhanced SHG efficiencies were obtained in Y-shaped ferrocenyl imidazole chromophores by n-octyl substitution. [Display omitted] [ABSTRACT FROM AUTHOR]

Donor-π-Acceptor type ferrocenyl 1,8-naphthalimide chromophores show aggregation induced enhanced emission (AIEE) at 60% of water fraction and second harmonic generation (SHG) efficiencies in bulk. [Display omitted] • FcPhNap-n-butyl (1) and Fc (Ph) 2 Nap-n-butyl (2) were synthesized and characterized. • Enhanced emission was achieved by AIEE process using THF/water mixture at 60%. • Chromophore 2 shows higher SHG efficiency than 1 due to the effective ICT process. • The optical and nonlinear optical properties were validated by DFT studies. A new ferrocene appended linear donor-π-acceptor (D-π-A) type 1,8-naphthalimide chromophores [FcPhNap- n -butyl (1) and Fc(Ph) 2 Nap- n -butyl (2)] have been synthesized and characterized using various analytical and spectroscopic techniques. The chromophores 1 and 2 show the one-electron transfer process, which was examined through cyclic voltammetric (CV) method. The solvatochromic studies show red shift by increasing the solvent polarity from non-polar to polar for both the chromophores 1 and 2 , due to the better stabilization of the more polarized excited state than the ground state in the polar solvent. The fluorescence studies show low fluorescence emission, which was enhanced by aggregation in THF/water mixture when the water ratio is increased upto 60%, due to the restricted intramolecular rotation (RIR) process in the aggregated state. Also, the quantum yield increases 3.4 (1) and 6.8 (2) times in the aggregation induced enhanced emission (AIEE) state than THF solution for both the chromophores [THF/AIEE = 0.05/0.17 for 1 and 0.03/0.22 for 2 ]. The second-order non-linear optical properties of the chromophores 1 and 2 were studied using Kurtz and Perry powder technique, chromophore 2 shows 1.2 times higher SHG efficiency than 1 , owing to the presence of additional phenyl group in 2 , which further supports the effective charge transfer process from donor to acceptor. Furthermore, optical and non-linear optical properties of chromophores 1 and 2 were analyzed by DFT/TD-DFT calculations using different functionals (B3LYP, long-range corrected CAM-B3LYP and LC-BLYP) with 6–31+G** level of theory. The B3LYP functional shows higher hyperpolarizability values [ β 0 = 109.2 × 10-30 esu (1), 299.7 × 10-30 esu (2)], due to the overestimation of the dipole moment, polarizability and hyperpolarizabilities between the donor–π–acceptor systems in B3LYP-hybrid functional, which leads to incorrect long-range charge transfer. [ABSTRACT FROM AUTHOR]

A new set of model chromophores derived from a truxene core fused with varied number and size of functionalized pyrazine units was designed and synthesized for the tentative exploration of possible connections between the molecular structure and their linear/nonlinear optical properties. The initial experimental results have indicated that these model compounds not only possess strong and widely dispersed two-photon absorption (2 PA) within the near-IR region but also show the ascending overall 2 PA when the molecular structure varies with increase in complexity and molecular weight, which implies that both the number of branches and the size of π-framework are important factors to the molecular 2 PA in this model chromophore system. On the other hand, the studied model chromophores also manifest very good photostability within their two-photon active spectral region even under a prolonged irradiation of IR laser pulses. In addition, a representative chromophore is selected to demonstrate optical power-limiting and power-stabilization performance against nanosecond laser pulses. [ABSTRACT FROM AUTHOR]

Using 4,9-dibromopyrene as a key intermediate, two new fused-core compounds, TP-PFF and TP-PFC-TP, were synthesized. These compounds not only exhibited excellent thermal stability but also yielded superior electroluminescence (EL) devices with a lower turn-on voltage, over 50% greater efficiency, and over 3 times longer lifetime than did a similar compound lacking a fused core. This new core-forming method can be applied in various applications with many different core groups. [ABSTRACT FROM AUTHOR]

Two porphyrin-chromophores, i.e. triad PorZn-(PorCOOH)2-(piper)2 (GZ-T1) and dyad (PorZn)2-NMe2 (GZ-D1), have been synthesized and their photophysical and electrochemical properties have been investigated. The optical properties together with the appropriate electronic energy levels, i.e. the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energy levels, revealed that both porphyrin assemblies can function as sensitizers for dye sensitized solar cells (DSSCs). The GZ-T1 and GZ-D1-based DSSCs have been prepared and studied using 20 mM CDCA as coadsorbent and were found to exhibit an overall power conversion efficiency (PCE) of 5.88% and 4.56%, respectively (under an illumination intensity of 100 mW cm−2 with TiO2 films of 12 μm). The higher PCE of the GZ-T1-sensitized DSSC, as revealed from the current–voltage characteristic under illumination and the incident photon to current conversion efficiency (IPCE) spectra of the two DSSCs, is mainly attributed to its enhanced short circuit current (Jsc), although both the open circuit voltage (Voc) and the fill factor are improved too. The electrochemical impedance spectra (EIS) demonstrated a shorter electron transport time, longer electron lifetime and higher charge recombination resistance for the DSSC sensitized with the dye GZ-T1 as well as a larger dye loading onto the TiO2 surface. [ABSTRACT FROM AUTHOR]

Mutations in the visual photoreceptor rhodopsin are the cause of the retinal degenerative disease retinitis pigmentosa. Some naturally occurring mutations 100 can lead to protein conformational instability. Two such mutations, N55K and G90V, 80 in the first and second transmembrane helices of the receptor, have been associated with sector and classical retinitis pigmentosa, respectively, and showed enhanced

Amine photobase generators (PBGs) are uncommon yet useful compounds. Rarer still are examples of PBGs that are active at visible wavelengths. We report the synthesis and characterization of new photolabile amine protecting groups that are active under visible light. The new chromophore, benzothiophene imino-phenylacetonitrile (BTIPA), was synthesized in four steps without use of chromatography and found to release any one of several amines upon exposure to 405 nm light. The chromophore was also demonstrated to be useful as a Merrifield synthesis protecting group. Experimental evidence suggests a sequential, two stage photolysis mechanism which leads to a nonlinear response to dose. [ABSTRACT FROM AUTHOR]

The mononuclear complex [Ni(pydc)(pydm)]·H2O, pyridine-2,6-dicarboxylato-2,6-bis(hydroxymethyl)pyridine nickel(ii) monohydrate, features a highly axially compressed pseudo-octahedral chromophore with significant rhombic contribution that is responsible for the sizable magnetic anisotropy of the Ni(ii) ion, D/hc≈−14 cm−1. This complex displays superparamagnetic behaviour in an applied external field that culminates at BDC = 0.2 T. Two relaxation processes are evidenced; the faster can be analyzed in terms of the Orbach, direct, and Raman processes yielding U/kB = 21.2 (±1.3) K and τ0 = 3.83 (±1.21) × 10−7 s. This is the first example of a field-induced single-molecule magnet in the class of hexacoordinate Ni(ii) complexes. [ABSTRACT FROM AUTHOR]

Reactions of 5-(9H-carbazol-9-yl)-isophthalate and metal salts provide laminar metal organic frameworks (MOFs) wherein interlayer interactions of the pendant carbazoles engender extended aromatic stacks or non-stacked structures with enhanced solid-state emission. These studies emphasize that MOFs serve as versatile supramolecular platforms to direct the aggregation and electroptical behaviours of organic chromophores. [ABSTRACT FROM AUTHOR]

The copper(I)-catalyzed 1,3-dipolar cycloaddition of 4-azido- (tetrafluorophenyl)boron-dipyrrin (azido-BODIPY) with diverse terminal alkynes, varying from simple alkyl-substituted derivatives to alkynes with functional groups and carbohydrates, was successfully employed to obtain meso-functionalized BODIPY derivatives through the 1,2,3-triazole linkage. The scope of this reaction was extended to the preparation of di- and trivalent BODIPY systems through the use of appropriate alkynyl linkers. Moreover, the synthesis of hydroxyl- and pentafluorothio-(SF5)-substituted, 1,2,3-triazole- linked array systems consisting of porphyrins and corroles as the central scaffold, in combination with a BODIPY, was investigated. These covalently connected tetrapyrrole- BODIPY arrays exemplify a versatile approach to the construction of multichromophore systems: the combination of 1,3-dipolar cycloaddition and nucleophilic substitution on pentafluorophenyl-substituted porphyrinoids. The systems designed herein could serve in various light-harvesting applications and electron-transfer studies. [ABSTRACT FROM AUTHOR]

Photosensitive nitroxides bearing different chromophore groups (benzophenone, naphthalene and quinoline) were synthesized and characterized. The photochemical properties of the synthesized products were investigated by UV−visible and fluorescence measurements. The results indicated that an efficient energy transfer from the chromophore moiety to the nitroxide radical moiety could occur within the molecular distances. The photo-induced nitroxide-mediated polymerization of methyl methacrylate ( MMA) was performed using the photosensitive nitroxide/2,2-dimethoxy-2-phenyl acetophenone as a bimolecular mediated system. The controlled character of the polymerization was confirmed by the linear tendency of molecular weight evolution with narrow molecular weight distribution (1.3−1.4). The experimental conditions, such as type of chromophore, initiator concentration and molar ratio of initiator/nitroxide, are discussed for a better understanding of the mechanism of the controlled polymerization. Using the polymerization products as macroinitiator, the chain extension reaction of MMA turned out to be able to re-initiate further polymerization of the monomer. © 2014 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Cyanobacteriochromes (CBCRs) are cyanobacterial photosensory proteins distantly related to phytochromes. Like phytochromes, CBCRs reversibly photoconvert between a dark-stable state and a photoproduct via photoisomerization of the 15,16-double bond of their linear tetrapyrrole (bilin) chromophores. CBCRs provide cyanobacteria with complete coverage of the visible spectrum and near-ultraviolet region. One CBCR subfamily, the canonical red/green CBCRs typified by AnPixJg2 and NpR6012g4, can function as sensors of light color or intensity because of their great variation in photoproduct stability. The mechanistic basis for detection of green light by the photoproduct state in this subfamily has proven to be a challenging research topic, with competing hydration and trapped-twist models proposed. Here, we use 13C-edited and 15N-edited ¹H-¹H NOESY solution nuclear magnetic resonance spectroscopy to probe changes in chromophore configuration and protein-chromophore interactions in the NpR6012g4 photocycle. Our results confirm a C15-Z,anti configuration for the red-absorbing dark state and reveal a ClS-E,anti configuration for the green-absorbing photoproduct. The photoactive chromophore D-ring is located in a hydrophobic environment in the photoproduct, surrounded by both aliphatic and aromatic residues. Characterization of variant proteins demonstrates that no aliphatic residue is essential for photoproduct timing. Taken together, our results support the trapped-twist model over the hydration model for the red/green photocycle of NpR6012g4. [ABSTRACT FROM AUTHOR]

An obvious limitation of the one-pass continuous dyeing process for polyester/cotton blends is its inability to achieve deep colour depth, which is caused by the low dye fixation yields of commercial reactive dyes. In this study, the performances of polyester/cotton blends dyed with high-fixation polymethylol dyes and disperse dyes were compared with those of polyester/cotton blends dyed with a mixture of reactive dyes and disperse dyes. Polymethylol dyes were observed to be suitable for dyeing polyester/cotton blends when used in low concentrations; the required concentrations of polymethylol dyes were only 23-58% of the concentrations of commercial reactive dyes required to reach a given colour level on polyester/cotton blends. The wash and crocking fastness of polyester/cotton blends dyed with polymethylol dyes were similar to those of polyester/cotton blends dyed with reactive dyes. [ABSTRACT FROM AUTHOR]

A novel series of styryl-based chromophores is synthesized, the constituents of which are characterized by UV–Vis, NMR, mass spectrometry, and thermal analysis. The chromophores show good solubility in MeOH, THF, and CH 2 Cl 2 . They also show good thermal stability for practical applications. Density functional theory calculations are employed in order to ascertain the structural, molecular, and electronic properties of the dyes. Moreover, the second order nonlinear optical (NLO) responses of the dyes are measured by the electric field induced second harmonic (EFISH) generation method. Relatively high scalar products of the vector component of the first hyperpolarizability tensor and the dipole moment vector ( μβ ) are obtained for some of the compounds. [ABSTRACT FROM AUTHOR]

Twoterrylene chromophores, 2,5,10,13-tetra(tert-butyl)terrylene(1) and 2,5-di(tert-butyl)terrylene(2), were synthesized and studied todetermine their singlet exciton fission (SF) efficiencies. Compound 1crystallizes in one-dimensional stacks, whereas 2packs in a slip-stacked, herringbone pattern of dimers motif. Stronglyquenched fluorescence and rapid singlet exciton decay dynamics areobserved in vapor-deposited thin films of 1and 2. Phosphorescence measurements on thin films of 1and 2show that SF is only 70 meV endoergic for thesechromophores. Femtosecond transient absorption experiments using lowlaser fluences on these films reveal rapid triplet exciton formationfor both 1(τ = 120 ± 10 ps) and 2(τ = 320 ± 20 ps) that depends strongly on film crystallinity.The transient absorption data are consistent with formation of anexcimer state prior to SF. Triplet exciton yield measurements indicatenearly quantitative SF in thin films of both chromophores in highlycrystalline solvent-vapor-annealed films: 170 ± 20% for 1and 200 ± 30% for 2. These results showthat significantly different crystal morphologies of the same chromophorecan both result in high-efficiency SF provided that the energeticsare favorable. [ABSTRACT FROM AUTHOR]

The article describes the synthesis of push-pull chromophores and an N-[4-(4-Methoxyphenoxy)butyl]carbazole moiety as a donor fragment. The different processes and the resulting compounds are detailed, which include subsequent alkylation of carbazole, acetylation, and Knoevenagel condensation. It is noted that the electrochemical properties of compounds synthesized were explored by cyclic voltammetry.

The effects of ultraviolet radiation (UVR) on the synthesis of mycosporine-like amino acids (MAAs) in sea-ice communities and on the other UV-absorption properties of sea ice were studied in a three-week long in situ experiment in the Gulf of Finland, Baltic Sea in March 2011. The untreated snow-covered ice and two snow-free ice treatments, one exposed to wavelengths ＞ 400 nm (PAR) and the other to full solar spectrum (PAR + UVR), were analysed for MAAs and absorption coefficients of dissolved (aCDOM) and particulate (ap) fractions, the latter being further divided into non-algal (anap) and algal (aph) components. Our results showed that the diatom and dinoflagellate dominated sea-ice algal community responded to UVR down to 25–30 cm depth by increasing their MAA : chlorophyll-a ratio and by extending the composition of MAA pool from shinorine and palythine to porphyra-334 and an unknown compound with absorption peaks at ca. 335 and 360 nm. MAAs were the dominant absorbing components in algae in the top 10 cm of ice, and their contribution to total absorption became even more pronounced under UVR exposure. In addition to MAAs, the high absorption by chromophoric dissolved organic matter (CDOM) and by deposited atmospheric particles provided UV-protection for sea-ice organisms in the exposed ice. Efficient UV-protection will especially be of importance under the predicted future climate conditions with more frequent snow-free conditions. [ABSTRACT FROM AUTHOR]

BOPHY dyes bearing bromo (in 5,5'-position) and iodo (in 4,4'-position) were synthesized. Double Knoevenagel reactions allow the extension of conjugation, resulting in an absorption above 625 nm. Selective cross-coupling reactions promoted by palladium(0) and microwave irradiation allow linking of a perylene module. These dyes are highly fluorescent, and the intramolecular cascade energy transfer from the perylene moiety to the BOPHY framework is almost quantitative, providing large virtual Stoke shifts (>5100 cm-1). [ABSTRACT FROM AUTHOR]

A novel fluorescence sensing system based on rhodamine 6G and 1,8-naphthalimide fluorophores was synthesized and investigated. The system was designed as a wavelength-shifting bichromophoric molecule where the 1,8-naphthalimide moiety is an energy “donor” capable of absorbing light and efficiently transferring the energy to a focal Rhodamine 6G “acceptor”. Furthermore, the 1,8-naphthalimide unit was configured on the “ fluorophore-spacer-receptor ” format. Thus, the distinguishing features of fluorescence resonance energy transfer systems were successfully combined with the properties of photoinduced electron transfer and classical ring-opening sensor systems. The synthesized compound shows excellent signalling properties towards protons as well as Cu 2+ and Hg 2+ over the representative metal ions. Due to the remarkable fluorescence changes in the presence of protons, Cu 2+ and Hg 2+ ions the novel system is able to act as a two output combinatorial logic circuit with three chemical inputs. [ABSTRACT FROM AUTHOR]

The understanding and description of collectively excited multichromophores is of crucial importance for many areas of basic and applied research. DNA has been used for the construction of well-defined heterochromophoric stacks. Electronic coupling among non-adjacent chromophores of the same type leads to the co-existence of PDI and pyrene H-aggregates in hybrids composed of alternating chromophore stacks. [ABSTRACT FROM AUTHOR]

A novel highly luminescent tris-fluorenyl ring-interconnected chromophore tris(DPAF-C9) was synthesized using a C3 symmetrical triaminobenzene core as the synthon. This structure bears three light-harvesting 2-diphenylamino-9,9-dialkylfluorenyl (DPAF) ring moieties with each attached by two branched 3',5',5'-trimethylhexyl (C9) arms. A major stereoisomer was chromatographically isolated and characterized to possess a 3D structural configuration of cis-conformer in a cup-form. Molecular calculation at B3LYP/6-31G* level revealed the unexpected stability of this cis-cup-conformer of tris(DPAF-C9) better than that of the stereoisomer in a propeller-form and the trans-conformer. The structural geometry is proposed to be capable of minimizing the aggregation related self-quenching effect in the condensed phase. Fluorescence emission wavelength of tris(DPAF-C9) was found to be in a close range to that of PVK that led to its potential uses as the secondary blue hole-transporting material for enhancing the device property toward the modulation of PLED performance. [ABSTRACT FROM AUTHOR]

A new chiral and multichromophoric macromolecular system based on a perylene diimide chromophore consisting of two 1,4-bis(3-aminopropyl) piperazine linkers and two terminal chiral naphthalene bisimide chromophores has been synthesized. All of the chromophoric units are not π-conjugated with each other and could behave independently due to the presence of the nonconjugated linker. A new symmetrical dehydroabietyl substituted naphthalene diimide was also synthesized for comparison purposes. The bulky and chiral substituent is included at the peripheral positions of macromolecular system to increase the solubility and introduce directionality to the intermolecular interactions. The multichromophoric macromolecule showed new and distinctive photophysical properties that are different from the properties in the monomeric states of the components and in blends. It exhibited strong absorption in a wide range (320–600 nm) with enhanced light absorption due to higher molar absorption coefficients. It is observed that the absorption, emission and electrochemical characteristics are delicate interplay among intermolecular interactions in the macromolecule both in solutions and solid-state. Photoinduced electronic excitation energy transfer was noticed in various solvents from energy-harvested peripheral chromophores to the centered perylene core. [ABSTRACT FROM AUTHOR]

The water diluted solution behaviour of mono- and bis-β-cyclodextrin (mono- and bis-CD) derivatives, whose appended groups and inter-CD linkers contain a naphthoxy chromophore moiety, has been studied using steady-state and time-resolved fluorescence techniques, circular dichroism and molecular modelling. Mono-CD derivatives form non-covalent dimeric tail-to-tail supramolecular structures via the mutual partial penetration, through their primary sides, of axially oriented naphthoxy appended groups and the self-inclusion of the naphthoxy moiety is rather improbable. Non-covalent dimer formation may compete with any guest complexation. Nevertheless, these assemblies can be broken up by decreasing medium polarity or when the appended group is captured by macrorings such as cucurbit[7]urils or native βCDs. Bis-CD derivatives, however, do not exhibit self-association processes which were observed in the mono-derivatives. This is because the presence of the bulky naphthoxy group in the spacer keeps the βCD cavities, which are capable of accommodating an external guest, away from each other. The dinaphthoxy group, in the bis-NβCD, was located in a quasi-parallel plane conformation between both CDs. [ABSTRACT FROM AUTHOR]

Two novel metal complexes, namely [Tb(L)(HO)]⋅(NO)⋅L⋅(HO) ( 1) and [Hg(L)Cl] ( 2), were obtained by the reaction of D-π-A (D = donor, π = conjugated spacer, A = acceptor) type pyridinium inner salt dye, trans-4-[( p- N, N-dimethylamino)styryl]- N-(2-propanoic-acid) pyridinium ( L) with corresponding metal salts. Single crystal X-ray diffraction analyses reveal that compound 1 possesses dinuclear motif in which two Tb(III) ions are linked by four carboxylate groups while complex 2 exhibits 1D chain structure based on Hg(II) ions bridged by carboxylate groups. The linear and non-linear optical properties of complexes 1 and 2 have been studied. Both 1 and 2 exhibit intense single-photon excited fluorescence (SPEF) and two-photon excited fluorescence (TPEF) in the red range. Results show that the replacement of central ions from Hg to Tb influence the two-photon absorption cross-section significantly through increasing the density of the chromophore. However, the peak positions of two-photon excited fluorescence are only slightly affected. Compared with L molecule, complex 1 shows enhanced two-photon absorption cross-section and decreased fluorescent lifetime. [ABSTRACT FROM AUTHOR]

Bis chromophores were synthesized by the terephthalaldehyde with (4-nitrophenyl) acetonitrile/(4-flurophenyl) acetonitrile under microwave irradiation. Bis-chromophores were obtained in good to excellent yields. The structures of bis-chromophores were established by FT-IR, 1 H NMR, 13 C NMR, EI-MS and elemental analyses. Physical chemical properties such as singlet absorption, extinction coefficient, stokes shift, oscillator strength and dipole moment, were investigated by UV–Vis and fluorescence spectroscopy measurements. Further we also measured the nonlinear refractive index and nonlinear absorption coefficients of these compounds using the single beam z-scan technique with a cw argon ion laser at 514.5 nm at different concentrations in DMSO solvent. The third order nonlinear susceptibility was estimated from these measurements and it shows high nonlinearity. The high negative refractive index makes these compounds suitable for optical limiting application. [ABSTRACT FROM AUTHOR]

To explore new 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY)-derived metal-organic frameworks (MOFs), we employed 2,6-dicarboxyl-1,3,5,7-tetramethyl-8-phenyl-4,4-difluoroboradiazaindacene (H2L) as a ligand to successfully synthesize five coordination polymers, namely, {[Zn2(L)2(bpp)].2H2O.2EtOH}n (1), {[Cd2(L)2(bpp)].2H2O.EtOH}n (2), {[Cd2(L)(bpe)3(NO3)2].2H2O.DMF.EtOH}n (3), {[Cd(L)(bpe)0.5(DMF)(H2O)]}n (4), and {[Cd(L)(bpe)0.5].1.5H2O.DMF}n (5) (bpp = 1,3-bi(4-pyridyl)propane, bpe = 1,2-bi(4-pyridyl)ethane). Except for two 2D-layer coordination polymers 3 and 4, the rest samples exhibit 3D metal-organic frameworks with certain pore sizes, especially MOFs 1 and 5. Spectroscopic and crystallographic investigations demonstrate that the absorption and emission energies of the BODIPY chromophores are sensitive to the coordination modes. Moreover, in case 2, the transition metal centers coordinated with the dicarboxylate ligands L2- are capable of forming the two BODIPY units in coplanar arrangements (θ = 37.9°), simultaneously suppressing the uncommon J-dimer absorption band centered at 705 nm with a long tail into the near-infrared region at room temperature. On the other hand, in comparison with the ligand H2L, the emission of monomer-like BODIPY in case 3 is enhanced in the solid state by a considerably long distance between the parallel BODIPY planes (about 14.0 Å). [ABSTRACT FROM AUTHOR]

Two chromophores C1 and C2 based on a fluorene electron donor with different π-electron bridges and the same electron acceptor have been synthesized and systematically characterized using NMR, MS and UV-vis absorption spectra. The energy gap between the ground state and the excited state and molecular nonlinearity were studied using UV-vis absorption spectroscopy, Density Functional Theory calculations and cyclic voltammetry measurements. The different properties between C1 and C2 were systematically compared. The results showed that C2 had a better performance than C1. The electrooptic coefficient of a poled film containing 25 wt% of C2 doped in amorphous polycarbonate afforded a value of 40 pm V−1 at 1310 nm. In addition, the excellent thermostability of C2 made itself a favourable candidate for practical application. [ABSTRACT FROM AUTHOR]

Fused cyclobutenes, prepared by the photocycloaddition of propargyl alcohols to cyclic anhydride chromophores, undergo facile thermochemical ring opening to fused γ-lactones. The size of the fused ring profoundly influences the temperature that is required to facilitate the ring opening (from 50 °C to 180 °C) and the nature of the product that is formed. Our studies provide new insights into the mechanistic course of these reactions and have been extended to facilitate the preparation of lactams fused to medium-sized rings. [ABSTRACT FROM AUTHOR]

Here we describe the synthesis and characterization of a range of symmetric two photon absorbing chromophores containing photoswitchable Disperse Red-type donors. These have been incorporated into D–π–D molecules with 1-(2-ethylhexyloxy)-4-methoxybenzene and 9,9-bis(2-ethylhexyl)-fluorene π-cores, and D–π–A–π–D molecules based on a (2,6-dimethyl-pyran-4-ylidene)propanedinitrile acceptor core. The TPA cross section measured by z-scan at 780 nm was up to 298 GM for the D–π–A–π–D molecules and up to 1250 GM for the molecules with D–π–D architectures. As all of the compounds have azo groups as part of the π linker the cis/trans isomerisation of these materials was also explored. It is found that dyes based on the D–π–D architecture are more amenable to isomerisation and are also more stable in the cis form when compared to D–π–A–π–D chromophores. [ABSTRACT FROM AUTHOR]

Three chromophores ZR1 , ZR2 and ZR3 based on the electron donor bearing different lengths of alkoxy chains, the same π-electron bridge and tricyanofuran acceptor, have been synthesized and systematically investigated. Density Functional Theory calculations and cyclic voltammetry measurements suggested that ZR2 (with hexyloxy) and ZR3 (with octoxy) had relatively small energy gaps between ground state and excited state than ZR1 (with butoxy) due to the auxiliary electron-donating ability and steric hindrance of their longer alkoxy chains on the donor. The electro-optic coefficient of poled films containing 20% wt of the new dyes doped in amorphous polycarbonate afforded values of 48, 62 and 65 pm/V at 1310 nm for ZR1 , ZR2 and ZR3 respectively. These results indicated that the introduction of the longer alkoxy chains on the donor could effectively reduce the intermolecular electrostatic interactions and aid the alignment of the chromophores. This conclusion is conducive to future molecular design. [ABSTRACT FROM AUTHOR]

Three-chromophore systems with light-harvesting behavior were prepared, which are based on periodic mesoporous organosilica (PMO) with crystal-like ordered structure. The organic bridges of biphenyl-PMO in the pore walls act as donors and two types of dye are incorporated in the one-dimensional channels. Consecutive two-step-Förster resonance energy transfer is observed from the biphenyl moieties to mediators (diethyl-aminocoumarin or aminoacridone), followed by energy transfer from mediators to acceptors (dibenzothiacarbocyanine, indodicarbocyanine, sulforhodamine G). High energy-transfer efficiencies ranging from 70 to 80% are obtained for two-step-FRET, indicating that the mesochannel structure with one-dimensional ordering provides spatial arrangement of chromophore pairs for an efficient direct energy transfer. The emission wavelength can be tuned by a choice of acceptor dye: 477 nm (diethylaminocoumarin), 519 nm (aminoacridone), 567 nm (sulforhodamine G), 630 nm (dibenzothiacarbocyanine), and 692 nm (indodicarbocyanine). [ABSTRACT FROM AUTHOR]

The synthesis and characterization of a new type of chromophore, namely PePc consisting of a central phthalocyanine core and four fused perylene-bisimide (PBI) units is described for the first time. The entire architecture represents a highly extended conjugated heterocyclic π-system with C4h symmetry. In order to guarantee pronounced solubility in organic solvents the corresponding PBI units were bay-functionalized with tert-butylphenoxy substituents. Next to the metal-free macrocycle, PePcH2, also metallated macrocycles PePcM (M=Zn, Ni, Pb, Ru, Fe) were synthesized. The extensive fusion of the corresponding aromatic building blocks to the very large extended π-system leads to a very narrow HOMO-LUMO gap and as a consequence to transparency in the visible but light absorption in the NIR region. Significantly, the azomethine N-atoms N1-N4 of PePcM and PePcH2 are highly basic. The corresponding tetraprotonated systems can only be deprotonated with very strong non-nucleophilic bases such as phosphazene bases. In the protonated forms PePcMH4 4+ and PePcMH6 4+ the absorption maximum is shifted back to the visible region due to the loss of conjugation. The experimental findings were corroborated with quantum mechanical calculations. [ABSTRACT FROM AUTHOR]

The new conjugated cruciform chromophores with donor–acceptor character, 1,4-dithienyl-2,5-bis(diphenylamino-phenyl)benzene ( 2 ) and 1,4-bis((5-(E)-2-(5-octylthiophen-2-yl)vinyl)thiophen-2-yl)-2,5-bis(diphenylamno-phenyl)benzene ( 3 ), were synthesized by Suzuki and Stille coupling reaction, respectively. Compounds 2 and 3 provided with a certain crystal character. In addition, compound 2 showed bright green emission in both CH 2 Cl 2 solution and solid film. However, compound 3 showed green emission in CH 2 Cl 2 solution and orange emission in solid film, which was attributed to the intermolecular interaction. The cyclic voltammetry (CV) and density functional theory (DFT) researches indicated that the symmetry crossing branches mainly influenced the lowest unoccupied molecular orbital (LUMO) levels. Moreover, DFT investigation indicated that compound 2 possessed the linear charge transfer pathway, and compound 3 may possess three different types of charge transfer pathways in excited state. [ABSTRACT FROM AUTHOR]

Conjugated oligothiophene chromophores are compared and studied for designing large linear and nonlinear absorption cross-sections. Optical properties of chromophores synthesized by the Naval Research Laboratory are modeled to construct a design factor of merit to predict and understand two-photon absorption (TPA) designs. Computer modeling to optimize parameters to produce photo active chromophores is conducted. Geometry, π -center (electron relay) and the electron donor or acceptor groups attached to the π -centers are considered for importance in TPA. This work could serve equally well as guide for quick back of the envelop research or industrial design verifications as well as an outline for introducing computation methods to students. [ABSTRACT FROM AUTHOR]

A new fluorene substituted methoxybenzene-pyrene chromophore ( 3 ), [1-(9,9-dimethylfluorene)-8-(4-methoxyphenyl)]pyrene, was synthesized by the Suzuki cross-coupling reactions of 1,8-dibromopyrene with 4-methoxyphenylboronic acid and 9,9-dimethylfluorene-2-boronic acid pinacol ester, respectively. The hexameric compound ( 5 ), hexakis{1-oxyphenyl-8-(9,9-dimethylfluorene)pyrene} cyclotriphosphazene, was prepared by a nucleophilic displacement reaction of hexachlorocyclotriphosphazene, N 3 P 3 Cl 6 , with ( 4 ), [1-(9,9-dimethylfluorene)-8-(4-hydroxyphenyl)]pyrene, which was obtained from the deprotection of compound ( 3 ). The newly synthesized compounds were fully characterized by standard spectroscopic techniques. The spectral properties of compound ( 5 ) were investigated by thermogravimetric analysis, differential scanning calorimetry, UV–Vis and fluorescence spectroscopy, and cyclic voltammetry. In addition, fluorescence quantum yields, fluorescence lifetimes and fluorescence quenching behavior by 1,4-benzoquinone were investigated in dichloromethane. It was found that the hexameric compound ( 5 ) emitted in the blue-light spectral region with a maxima of 455 nm, with a quantum yield of 0.63 in dichloromethane. Compound ( 5 ) was amorphous in nature and exhibited excellent thermal stability, with a decomposition temperature of 498 °C and a high glass-transition temperature of 58 °C. [ABSTRACT FROM AUTHOR]

We report the C-Hπ H-C and C-Hπ π interaction assisted formation of thermodynamically stable blue emissive AP-I from the kinetically stable green emissive AP-II crystal polymorph of 1-(anthracen-9-yl) pyrene (AP). The rotational degree of freedom at the bond between the two constituent chromophores facilitates the formation of conformational polymorphs AP-I and AP-II that can be quantitatively crystallized from ethyl acetate and hexane, respectively. [ABSTRACT FROM AUTHOR]

No Abstract [ABSTRACT FROM AUTHOR]

A new series of ferrocene (D) and methoxyphenyl (D′) conjugated D-D′-π-A push-pull chromophores [Fc-(RPh)C=CH–CH=CN-R'{R, R' = H, CN (1), OCH 3 , CN (2), H, C 6 H 4 NO 2 (3), OCH 3 , C 6 H 4 NO 2 (4)}] were synthesized and spectroscopically characterized. The structure of the chromophore 3 was confirmed by single crystal X-ray diffraction studies, and it was crystallized in triclinic crystal system with P-1 centrosymmetric space group. In the crystal packing, several non-covalent interactions (H-bonding and C–H·····π) were observed. The thermal behaviour of the chromophores 3 and 4 has been investigated using thermogravimetric analysis and was found to be stable up to 230 °C. The solvatochromic studies of the chromophores 1 – 4 showed a positive solvatochromism with red-shift from non-polar to polar solvents due to the high dipolar excited state in the presence of strong electron-donor and acceptor moieties. The electrochemical performance of the chromophores revealed the one-electron transfer from the ferrocene to ferrocenium ion Fe 2 + ⇌ Fe 3 + . The chromophores 1 – 4 exhibited low fluorescence intensity and quantum yield as a consequence of the quenching nature of ferrocene, it was further enhanced through the aggregation-induced emission (AIE) process in THF/H 2 O mixtures by the restriction of intramolecular rotation (RIR), and the chromophores 1 – 4 showed 2 times higher quantum yield in the aggregated state. The second-order nonlinear optical response was attained by Kurtz-Perry powder technique. The second harmonic generation (SHG) efficiencies of the chromophore 4 was close to the standard KDP, owing to the presence of multi-donor [Ferrocene (D) and methoxyphenyl (D′)] and acceptor groups with extended π-conjugation. In addition, the mesomeric effect (+M) of the methoxy group makes an effective charge transfer process. The optical and nonlinear optical properties of the chromophores were further analyzed by density functional theory (DFT) with different functionals (B3LYP, CAM-B3LYP and LC-BLYP). The hyperpolarizability values were underestimates in the B3LYP-hybrid functional because of the corrected long-range charge transfer between donor and acceptor in the D-π-A systems. The frontier molecular orbital (FMO) level helps for better understanding the charge transfer, nonlinear optical (NLO) properties, and the calculated HOMO-LUMO energy levels were in good agreement with the experimental results. [Display omitted] • Multi donor-acceptor ferrocenyl chromophores 1 – 4 were synthesized and structurally characterized. • The chromophore 4 shows enhanced SHG, due to the presence of multi donors and acceptor. • The weak to strong emission was observed in AIE state at 70% of THF/H 2 O. • The experimental results were validated with DFT and TD-DFT calculations using B3LYP, CAM-B3LYP and LC-BLYP with 6–31+ G** basis set. [ABSTRACT FROM AUTHOR]

Deep eutectic-solvothermal synthesis has been successfully employed to prepare four polyoxo-titanium clusters (PTCs), with nuclearity up to 28. The cluster cores obtained via this method are completely functionalized by conjugated ligands and display different photocatalytic H2 production activities. [ABSTRACT FROM AUTHOR]

This minireview reflects the most significant advances in the synthesis of promising nonlinear-optical chromophores over the last 5-10 years. We focus on the studies of chromophores combining an electron-donating moiety with an electron-withdrawing 3-cyano-2-(dicyano)methylene-2,5-dihydrofuran-4-yl group through a linker containing a polyene motif or one to two five-membered heterocycles. [ABSTRACT FROM AUTHOR]

We present the synthesis of a macrocyclic ruthenium(II) complex that combines the versatile photophysics and supramolecular chemistry of biimidazole ruthenium(II) chromophores with a macrocyclic geometry that allows for its introduction into mechanically interlocked frameworks. Structural information on the core framework was gained from a solid-state structure. The new supramolecular building block shows that the principal photophysics of the ruthenium chromophore, that is, the cation-driven light-switch effect, are retained during the formation of the macrocycle. [ABSTRACT FROM AUTHOR]

The synthesis and photophysical properties of two novel multichromophoric compounds is presented. Their molecular design comprises a carbonyl-bridged triarylamine core and either naphthalimides or 4-(5-hexyl-2,2′-bithiophene)naphthalimides as second chromophore in the periphery. The lateral chromophores are attached to the core via an amide linkage and a short alkyl spacer. The synthetic approach demonstrates a straightforward functionalization strategy for carbonyl-bridged triarylamines. Steady-state and time-resolved spectroscopic investigations of these compounds, in combination with three reference compounds, provide clear evidence for energy transfer in both multichromophoric compounds. The direction of the energy transfer depends on the lateral chromophore used. Furthermore, the compound bearing the lateral 4-(bithiophene)naphthaimides is capable of forming fluorescent gels at very low concentrations in the sub-millimolar regime whilst retaining its energy transfer properties. [ABSTRACT FROM AUTHOR]