Exploring Favorable Supramolecular Interactions of Multifluorinated Aromatics in Dendronized Push-Pull Chromophores for Electro-Optics

Multifluorinated aromatics serve as supramolecular synthons in the research of organic electro-optic (EO) materials by exploiting π-π stacking interaction between the aromatic hydrocarbon and multifluorinated aromatic groups for performance improvement. However, non-classical hydrogen bonding remains largely unexplored in fluorinated EO dendrimers. In this study, three Fréchet-type generation 1 benzyl ether co-dendrons were synthesized by replacing one benzyl group with 2,3,5,6-tetrafluorobenzyl (p-HF4Bz), pentafluorobenzyl (C6F5Bz), and 2,3,4,5-tetrafluorobenzyl (o-HF4Bz) groups, to afford the benzoic acid derivatives D1, D2, and D3, which were further bonded to the donor and π-bridge moieties to afford three co-dendronized push-pull phenyltetraene chromophores EOD1, EOD2, and EOD3, respectively. The weak C-H⋅⋅⋅X (X=O, F) interactions in the crystal structure of D1 cumulatively add to the benzoic acid dimers to form an extended hydrogen-bonded network, while D2 is crystallized into a centric one-dimensional chain with strong intermolecular interactions. The poled films of EOD1 with PMMA exhibited the largest and most stable EO activity with optical homogeneity among the series. The results identify the effectiveness of weak but favorable hydrogen bonds enabled by the enhanced carbon acidity of p-HF4Bz synthon in D1, over the interactions in D2 and D3, for the rational design of supramolecular EO dendrimers.

Nonlinear optical properties DFT calculations of polyacethylene and copolymers models substituted with aldimines chromophores as side chains

Aldimine derivatives chromophores grafted on polyacetylene oligomers were first designed to investigate the nonlinear optical (NLO) response of the resulting materials using CAMB3LYP method. The effects of different factors such as the chain length separating the substitutions as well as the configurations and the orientations of these latter, were examined and discussed. In a second part of this paper, NLO responses, in particular the static hyperpolarizabilities of polyvinyl oligomers substituted by aldimine chromophores via carboxylic groups and by pyrrolidone groups were calculated for different configurations. The stability and the hydrogen bonding in each oligomer were also discussed.

Probing Polymer Chain Folding in Solution Using Second Harmonic Light Scattering

Periodically grafted amphiphilic copolymers (PGACs) were earlier shown by us to adopt a zigzag folded conformation in the solid state, which enabled the backbone and pendant segments to segregate and occupy alternate layers in a lamellar structure. The conformational transition from a random coil to a zigzag folded chain in solution is an interesting problem, which is largely unexplored. To examine this, an orthogonally clickable parent polyester was sequentially clicked with two types of poly(ethylene glycol) (PEG) segments: one is a simple PEG and the other is a PEG that carries a dipolar chromophore. These two hydrophilic PEG segments, installed in a periodic and alternating fashion along the hydrocarbon-rich (HC) polyester backbone, ensure that the Janus folded chains are formed upon folding and carry chromophoric dipoles oriented along the same direction, thereby generating a large net dipole. The folding-induced alignment of chromophores in solution was followed using second harmonic light scattering (SHLS), wherein the intensity of the frequency-doubled scattered light (I_2ω) is measured. Folding was induced by adding a polar solvent, like methanol, to a chloroform solution of the polymer; methanol desolvates the HC backbone but solubilizes the pendant PEG segments, thus inducing folding. The second harmonic intensity (I_2ω) increased initially with methanol concentration and then saturated; in contrast, I_2ω remained invariant with the solvent composition in the case of an analogous model chromophore. Furthermore, in a model PGAC carrying chromophore-bearing PEG segments on every repeat unit, I_2ω decreased with increasing methanol composition, revealing the formation of a centrosymmetric folded chain, wherein the chromophoric dipoles on either side cancel each other. Thus, this study clearly reveals that the zigzag chain folding of PGACs can be induced by a segment-selective solvent, resulting in the rather elusive directional ordering of chromophoric dipoles in solution.

Laser performance and investigation of the optimal density functional and the dependence of the basis sets for (E, E)-2,5-bis (3,4-dimethoxystyryl) pyrazine (BDP) molecule

This manuscript includes some photophysical parameters and some optical properties such as absorption and emission spectra of the (E, E)-2,5-bis (3,4-dimethoxystyryl) pyrazine (BDP) by applying sol–gel and copolymer matrices. The BDP molecular structure is incorporated in sol–gel matrix and copolymer of methyl methacrylate (MMA) and 2-hydroxyethyl methacrylate (HEMA). In case of sol–gel matrix, the BDP molecular structure has higher quantum yield in addition to photostability maxima. The laser behavior of this molecular structure containing sol–gel matrix is good senior compared to copolymer one via using diode laser (450 nm) as pumping laser of power 160 mW. Also, the fluorescence profile of the BDP molecular structure is sensitized via using cadmium sulfide (CdS) quantum dots (QDs) by applying sol–gel host. The optimized structure of the BDP molecule is obtained via applying B3LYP/6-31G(d) level of theory. The electronic absorption and emission spectra of the BDP molecular structure in ethanol solvent were calculated using time-dependent density functional theory (TDDFT) at CAM-B3LYP/6-31G +  + (d, p) level. The obtained theoretical results were compared to experimental ones.

Hyperbranched Macromolecules: From Synthesis to Applications

Hyperbranched macromolecules (HMs, also called hyperbranched polymers) are highly branched three-dimensional (3D) structures in which all bonds converge to a focal point or core, and which have a multiplicity of reactive chain-ends. This review summarizes major types of synthetic strategies exploited to produce HMs, including the step-growth polycondensation, the self-condensing vinyl polymerization and ring opening polymerization. Compared to linear analogues, the globular and dendritic architectures of HMs endow new characteristics, such as abundant functional groups, intramolecular cavities, low viscosity, and high solubility. After discussing the general concepts, synthesis, and properties, various applications of HMs are also covered. HMs continue being materials for topical interest, and thus this review offers both concise summary for those new to the topic and for those with more experience in the field of HMs.

Electric-field-induced nonlinear optical switches of all-metal spherical aromatic molecules with infrared transparency: a theoretical study

Two new all-metal spherical aromatic molecules Be₆Li₈ and Be₆Li₁₄ have been designed theoretically.

Photo-crosslinkable second-order nonlinear optical polymer: facile synthesis and enhanced NLO thermostability

A new photo-crosslinkable second-order nonlinear optical system was designed and prepared by azido-yne and the thiol–ene click reactions.

V, Murugakoothan P. Crystal structure, molecular packing, FMO, NBO, nonlinear optical and optical limiting properties of an organic imidazolium diphenylacetate diphenylacetic acid single crystal

A new organic nonlinear optical material, imidazolium diphenylacetate diphenylacetic acid, with excellent structural characterization and nonlinear optical activity has been reported.

Preparation of Main-Chain Polymers Based on Novel Monomers with D-π-A Structure for Application in Organic Second-Order Nonlinear Optical Materials with Good Long-Term Stability

Main-chain nonlinear optical polymers based on novel chromophores with special structures presented good solubility in most of the organic solvents. Polymers PE-1 and PE-2 attained the thermal decomposition temperatures of 305 and 223 °C and glass transition temperatures of 113 and 108 °C, and exhibited only negligible decay in the SHG signal baked at 85 °C over hundreds of hours, respectively. The SHG coefficients of poled films from polymers PE-1 and PE-2 were 26.3 and 35.8 pm/V, respectively. These results indicated that this class of polymers can be used in the preparation of organic electro-optic devices.

Synthesis, photophysical properties and DFT analysis of highly substituted pyrido carbazole-based “push pull” chromophores

A series of new fluorescent pyrido[2,3-a]carbazole derivatives were synthesized based on a four component reaction with 2,3,4,9-tetrahydro-1H-carbazol-1-one, malononitrile, and aryl/heteroaryl aldehydes in presence of NaOEt.

The use of azide-alkyne click chemistry in recent syntheses and applications of polytriazole-based nanostructured polymers

The rapid development of efficient organic click coupling reactions has significantly facilitated the construction of synthetic polymers with sophisticated branched nanostructures. This Feature Article summarizes the recent progress in the application of efficient copper-catalyzed and copper-free azide-alkyne cycloaddition (CuAAC and CuFAAC) reactions in the syntheses of dendrimers, hyperbranched polymers, star polymers, graft polymers, molecular brushes, and cyclic graft polymers. Literature reports on the interesting properties and functions of these polytriazole-based nanostructured polymers are also discussed to illustrate their potential applications as self-healing polymers, adhesives, polymer catalysts, opto-electronic polymer materials and polymer carriers for drug and imaging molecules.

Synthesis of asymmetric dendrimers with controllable chromophore concentration and improved electro-optical performance

In this work, we provided a simple work-up procedure to prepare a new kind of electro-optical dendrimer with an asymmetric configurationviaa Cu-(i) catalyzed Huisgen-reaction.

A series of dendronized hyperbranched polymers with dendritic chromophore moieties in the periphery: convenient synthesis and large nonlinear optical effects

Excellent optical transparency and NLO coefficients were achieved by introducing dendritic chromophore moieties to the periphery of dendronized hyperbranched polymers.

Improved poling efficiency of polyurethanes containing spindle-like chromophores by a functional group tuning for nonlinear optic (NLO) materials

Spindle-like chromophores suspended in polyurethane NLO materials could be oriented without any other doped polymers and exhibited satisfactory temporal stability performance.

Design and preparation of hybrid films containing three-branched chromophores for nonlinear optical applications

A new hybrid film with homogeneous morphology is fabricated and exhibits excellent second nonlinear optical properties.

Synthesis and characterization of two novel second-order nonlinear optical chromophores based on julolidine donors with excellent electro-optic activity

Second order NLO chromophores with julolidine donor.

Asymmetric dendrimers with improved electro-optic performance: synthesis and characterization

A new series of electro-optical dendrimers with asymmetric configurations was synthesized through a Cu-(I) catalyzed Huisgen reaction.

Spectroscopic investigation, photophysical parameters and DFT calculations of 4,4'-(1E,1'E)-2,2'-(pyrazine-2,5-diyl)bis(ethene-2,1-diyl)bis(N,N-dimethylaniline) (PENDA) in different solvents

A comprehensive investigation on the photophysics of a π-conjugated potential push-pull chromophore system 4,4'-(1E,1'E)-2,2'-(Pyrazine-2,5-diyl)bis(ethene-2,1-diyl)bis(N,N-dimethylaniline) (PENDA) has been carried out spectroscopically. The optical absorption and emission properties of this molecule have been studied in different solvents. The molecule PENDA shows strong solvatochromic emission upon changing the solvent polarity from nonpolar to polar; indicating that emission state is of intramolecular charge transfer (ICT) character. The solvent effect on the spectral properties such as singlet absorption, molar absorptivity, oscillator strength, dipole moment and fluorescence quantum yield of PENDA have been studied in detail. Lippert-Mataga and Reichardt correlations were used to estimate the difference between the excited and ground state dipole moments (Δμ). Ground and electronic excited states geometric optimizations were performed using density functional theory (DFT) and time-dependent density functional theory (TDDFT), respectively, with the Gaussian 09 package. A solution of (8×10(-5) M) PENDA in THF, dioxane, CH3CN and CHCl3 gives laser emission when pumped by a nitrogen laser pulse (λex=337.1 nm) of 800 ps duration and 1.48 mJ pulse energy. PENDA dye displays fluorescence quenching by colloidal silver nanoparticles (Ag NPs) in ethanol. The fluorescence data reveal that dynamic quenching and energy transfer play a major role in the fluorescence quenching mechanism.

The synthesis of new double-donor chromophores with excellent electro-optic activity by introducing modified bridges

New double-donor chromophores were synthesized and large hyperpolarizability can be effectively translated into large electro-optic coefficients.

Bulk crystal growth and nonlinear optical characterization of a stilbazolium derivative crystal: 4-[2-(3,4-dimethoxyphenyl)ethenyl]-l methylpyridinium tetraphenylborate (DSTPB) for NLO device fabrication

The search for organic crystals with highly efficient nonlinear optical (NLO) properties with a high surface laser damage threshold (LDT) has become more of a demand in the frontier areas of optical switching and communications applications.

Dendronized hyperbranched polymers containing isolation chromophores: design, synthesis and further enhancement of the comprehensive NLO performance

New dendronized hyperbranched polymers (DHPs) constructed by dendronized monomers, exhibit good comprehensive NLO performance, especially for thermostability.