Solid-emissive fluorophores constructed by a non-planar heteropolycyclic structure with bulky substituents: synthesis and X-ray crystal structures

Novel solid-emissive indeno[1,2-b]benzo[4,5-e]pyran-11-one-type fluorophores having non-planar structures with sterically hindered substituents (R = butyl, phenyl, and thienyl) have been designed and conveniently synthesized. The fluorescence quantum yields of in 1,4-dioxane were (Phi = 0.053) > (Phi = 0.013) > (Phi = 0.003). On the other hand, the solid-state fluorescence quantum yields of the fluorophores were (Phi = 0.39) > (Phi = 0.15) > (Phi = 0.06). To elucidate the large differences in the quantum yields in solution and in the solid state and among the fluorophores , we performed time-resolved fluorescence spectroscopic measurements, semi-empirical molecular orbital calculations (AM1 and INDO/S), and X-ray crystallographic analyses of . The comparison of the values of the radiative and non-radiative rate constants determined by the time-resolved spectroscopic measurements in solution and in the crystalline state supported that non-radiative decay is reduced by restriction of the rotation of the phenyl and thienyl rings in the solid state. In addition, the X-ray crystal structures demonstrated that, in and , the non-planar structure with sterically hindered substituents prevents the fluorophores from forming short pi-pi contacts and produces strong solid-state fluorescence. On the other hand, in the crystal of , the formation of continuous intermolecular CH[dot dot dot]S bonding between neighboring fluorophores was found to increase short pi-pi contacts and reduce the fluorescence intensity.     

A novel series of anthraquinone-based discotic liquid crystals with bulky substituents: synthesis and characterization

A novel series of anthraquinone-based discotic liquid crystals with bulky substituents, namely 1,5-dibenzyloxy-2,3,6,7-tetraalkyloxy-9,10-anthraquinones, has been synthesized starting from gallic acid. This is, to our knowledge, the first example of bulky substitution in a discotic C₂-symmetric molecule forming columnar phases. Except for the lowest homologue, all members of this series are found to exhibit columnar mesophases; the low temperature mesophase appears to be three-dimensionally ordered whereas the high temperature mesophase is hexagonal columnar (Col_h). We find that the introduction of benzyl substituents for alkyl chains (in the 1,5-positions) on the anthraquinone hexaalkoxylates stabilizes the three-dimensionally ordered phase, whereas it destabilizes the Col_h phase, compared with the anthraquinone hexaalkoxylates. Interestingly, the three-dimensionally ordered phase extends down to -50 °C, making these new derivatives suitable for device applications.     

A novel series of anthraquinone-based discotic liquid crystals with bulky substituents: synthesis and characterization

A novel series of anthraquinone-based discotic liquid crystals with bulky substituents, namely 1,5-dibenzyloxy-2,3,6,7-tetraalkyloxy-9,10-anthraquinones, has been synthesized starting from gallic acid. This is, to our knowledge, the first example of bulky substitution in a discotic C₂-symmetric molecule forming columnar phases. Except for the lowest homologue, all members of this series are found to exhibit columnar mesophases; the low temperature mesophase appears to be three-dimensionally ordered whereas the high temperature mesophase is hexagonal columnar (Col_h). We find that the introduction of benzyl substituents for alkyl chains (in the 1,5-positions) on the anthraquinone hexaalkoxylates stabilizes the three-dimensionally ordered phase, whereas it destabilizes the Col_h phase, compared with the anthraquinone hexaalkoxylates. Interestingly, the three-dimensionally ordered phase extends down to -50 °C, making these new derivatives suitable for device applications.     

Synthesis and characterization of soluble seco-porphyrazines with bulky substituents

By cyclotetramerization of 3,4-bis(4-tert-butylphenyl)pyrroline-2,5-diimine in the presence of magnesium butanolate, magnesium porphyrazinate with eight (4-tert-butylphenyl) units on the periphery has been synthesized. Its demetalation by the treatment with trifluoroacetic acid resulted in a partially oxidized product, namely, octakis(4-tert-butylphenyl)-2-seco-porphyrazine-2,3-dione. Further reaction of this product with copper(II) acetate, zinc(II) acetate, and cobalt(II) acetate led to the metallo derivatives, [octakis(4-tert-butylphenyl)-2-seco-2, 3-dioxoporphyrazinato]M(II) (M = Cu, Zn, Co). These soluble complexes have been characterized by elemental analysis, FT-IR, ¹H NMR, UV-Vis, and mass spectral data.     

A new class of long-wavelength fluorophores: strong red fluorescence, convenient synthesis and easy derivation

A new class of structurally simple fluorophores with strong long-wavelength emission have been developed through a very convenient procedure.     

A novel strategy for fluorescence enhancement in the solid-state: affording rigidity to fluorophores packing

Solid-state fluorescence enhancement was achieved by preparation of rigid packing that was afforded by disposition of benzylamine into tubulate spaces, serving as a powerful and useful strategy for the enhancement.     

酰基偶氮化合物的固态合成

固态合成具有高产率、高选择性、低能耗、无溶剂、环境污染小等优点[1]。偶氮化合物广泛地用作染料,分析试剂,非线性光学材料,激光盘信息存贮材料和现代彩色照相技术中的油溶性染料[2 8]。本文Fe(NO3)3·9H2O作为氧化剂,在室温无溶剂条件下,将芳基取代酰肼固态氧化为酰基偶氮化合物。产物的结构都经过了元素分析、IR和1HNMR谱表证。取1mmol取代酰肼和2mmolFe(NO3)3·9H2O于玛瑙研钵中混合均匀,室温下研磨6～8分钟后,混合物的颜色由浅色变为棕色。用10ml丙酮使混合物充分溶解,并移入小烧杯中,向烧杯中加入几滴盐酸,直到溶液的颜色…     

Synthesis and characterization of non-aggregating octa-substituted azaphthalocyanines bearing bulky phenoxy substituents

The synthesis and characterization of two novel series of octaazaphthalocyanines (AzaPc) bearing bulky phenoxy substituents are described. Target precursors to AzaPcs derivatives were prepared by using a nucleophilic aromatic substitution reaction between sterically hindered phenols (2,6-di-iso-propylphenol and 2,6-diphenylphenol) and 5,6-dichloropyrazine-2,3-dicarbonitrile. UV-vis and ¹H NMR analyses confirm that steric isolation of the AzaPcs cores enforced both in the solution and in the solid state. This study explores the effectiveness of the steric factor imposed by the applied bulky phenoxy substituents on the packing behaviour of azaphthalocyanines and thereby improving their solubility and photo-physical properties.     

The synthesis of chlorosilanes from alkoxysilanes,silanols, and hydrosilanes with bulky substituents

We have found that commercially important trialkylchlorosilanes can readily be synthesized by the reaction of alkoxysilanes, silanols, and hydrosilanes with aqueous concentrated hydorochloric acid. Treatment of trialkylalkoxysilanes bearing the bulky alkyl substituents, such as the i-Pr, sec-Bu, tert-Bu, and cyclo-Hex group, with 35% aqueous hydrochloric acid afforded the corresponding trialkylchlorosilanes in excellent yields. Similar treatment of trialkylsilanols with 35% aqueous hydrochloric acid also gave trialkylchlorosilanes in almost quantitative yields. The reaction of methyltrichlorosilane and dimethyldichlorosilane with alkyl-Grignard reagents bearing a bulky alkyl group, followed by treatment of the resulting mixtures with aqueous concentrated hydrochloric acid, produced the respective dialkylmethyl- and alkyldimethylchlorosilanes in high yields. Treatment of trialkylhydrosilanes with concentrated hydrochloric acid in the presence of a palladium catalyst afforded trialkylchlorosilanes in high yields.     

Synthesis and characterization of novel polyimides with bulky pendant groups

New dianhydrides containing t‐butyl and phenyl pendant groups have been synthesized and used as monomers, together with commercial diamines, to prepare novel polyimides. The influence of the chemical structure of the monomers on their reactivity has been studied by quantum semiempirical methods. The polyimides have been characterized by FTIR and by NMR in the case of soluble polymers. The presence of pendant groups and the method used to imidize polyimide precursors greatly affected polymer properties such as solubility, glass transition temperature, thermal stability, and mechanical properties. As a rule, the novel polyimides showed better solubility in organic solvents than the parent polyimides. Glass transition temperatures in the range 250–270°C and decomposition temperatures over 520°C were observed for the set of current polymers. Tensile strengths up to 135 MPa and mechanical moduli up to 3.0 GPa were measured on films of the current polyimides. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 805–814, 1999     

Tuning the solid-state luminescence of BODIPY derivatives with bulky arylsilyl groups: synthesis and spectroscopic properties

Boron dipyrromethenes (BODIPYs) with bulky triphenylsilylphenyl(ethynyl) and triphenylsilylphenyl substituents on pyrrole sites were prepared via Hagihara-Sonogashira and Suzuki-Miyaura cross-coupling with ethynyl-terminated tetraphenylsilane and boronic acid-terminated tetraphenylsilane. The chromophores are designed to prevent intermolecular π-π stacking interaction and enhance fluorescence in the solid state. Single crystals of 1?a and 2?b for X-ray structural analysis were obtained, and weak π-π stacking interactions of the neighboring BODIPY molecules were observed. Spectroscopic properties of all of the dyes in various solvents and in films were investigated. Triphenylsilylphenyl-substituted BODIPYs generally show more pronounced increases in solid-state emission than triphenylsilylphenyl(ethynyl)-substituted BODIPYs. Although the simple BODIPYs do not exhibit any fluorescence in the solid state (Φ=0), arylsilyl-substituted BODIPYs exhibit weak to moderate solid-state fluorescence with quantum yields of 0.03, 0.07, 0.10, and 0.25. The structure-property relationships were analyzed on the basis of X-ray crystallography, optical spectroscopy, cyclic voltammetry, and theoretical calculations.     

Synthesis and EPR studies of porphyrazines with bulky substituents

Magnesium porphyrazinate substituted with eight 4-tert-butylphenylthio-groups on the peripheral positions has been synthesized by cyclotetramerization of 1,2-bis(4-tert-butylphenylthio)maleonitrile in the presence of magnesium butanolate. The metal-free derivative was obtained by its treatment with trifluoroacetic acid and further reaction of this product with copper(II) acetate, zinc(II) acetate and cobalt(II) acetate led to the metal porphyrazinates (M = Cu, Zn, Co). These new compounds have been characterized by elemental analysis, together with FT-IR, ¹H NMR, UV–Vis spectral data. By using EPR technique, room temperature paramagnetic properties of Cu(II) doped porphyrazine sample as powder and solution forms were measured. The first-derivative EPR signals taken from as powder and solution forms shows that the sample is axially symmetric. The trend g_∥ > g_⊥ > 2 indicates that the unpaired electron is located mainly in the _dx2-y2${\mathrm{d}}_{x^2-y^2}$ orbital (²B₁ as ground state).     

Synthesis and mesophase characterization of liquid crystalline polyesters with bulky,rigid, lateral substituents

The synthesis and characterization of aromatic polyesters containing various symmetrically di-substituted hydroquinone monomers is described. The homopolyesters made from these monomers and terephthalic acid (TA) did not melt. Copolyesters of TA with mono- and di-substituted hydroquinone formed liquid crystalline melts. Optical microscopy showed schlieren, marbled, and droplet textures characteristic of the nematic phase. DSC experiments were also in accord with mesophase formation as multiple transitions characteristic of first-order phase changes were found. In general, the crystal-nematic transition was about 300°C, whereas the nematic-isotropic change was over 400°C. All the polyesters were prone to decomposition near or above the isotropization temperature. © 1994 John Wiley & Sons, Inc.     

Distyryl-boradiazaindacenes: facile synthesis of novel near IR emitting fluorophores

Boradiazaindacenes with methyl substituents at 3 and 5 positions were for the first time shown to undergo efficient double condensation reactions with an aromatic aldehyde yielding a series of extended conjugation dyes. These new fluorophores have absorption maxima in the range of 650-660 nm. The dyes reported here have large quantum yields with 20 nm Stokes' shifted emission peaks. The straightforward synthesis of such red shifted BODIPY derivatives is important in relation to the synthesis of novel and useful fluorescent chemosensors. In addition, this facile transformation may make these new fluorophores' building blocks in the construction of large functional supramolecular systems.     

Heterocyclic quinol-type fluorophores. Part 9: Effect of forming a continuous intermolecular hydrogen bonding chain between fluorophores on the solid-state fluorescence properties

Three heterocyclic quinol-type fluorophores with benzo[c]carbazol-6-one skeleton or benzo[b]naphtho[1,2-d]furan-6-one skeleton, 9-dibutylamino-5-hydroxy-5-phenyl-5,7-dihydro-benzo[c]carbazol-6-one (5a), 7-butyl-9-dibutylamino-5-hydroxy-5-phenyl-5,7-dihydro-benzo[c]carbazol-6-one (5b) and 9-dibutylamino-5-hydroxy-5-phenyl-5H-benzo[b]naphtho[1,2-d]furan-6-one (6c) have been synthesized and their photophysical properties have been investigated in solution and in the solid state. The fluorescence quantum yield (Φ) increases in the order of 5b (0.35)<5a (0.41)<6c (0.74) in 1,4-dioxane. On the other hand, the Φ value in the solid state increases in the order of 5a<<6C (0.03)<5b (0.07), which are much smaller than those in 1,4-dioxane. To elucidate the effects of molecular and crystal structures on the solid-state fluorescence properties, we have performed the semi-empirical molecular orbital calculations (AM1 and INDO/S) and X-ray crystallographic analysis. It was found that the formation of a continuous intermolecular hydrogen bonding between adjacent fluorophores is observed in the crystal of 5a, which is considered to cause a drastic fluorescence quenching in the solid state.     

Rational design and convenient synthesis of a novel family of ruthenium complexes with O,N-bidentate ligands

A two step procedure for the synthesis of a novel family of homogeneous and immobilized Ru-complexes containing Schiff bases as O,N-bidentate ligands is described. The new Ru-complexes have been structurally characterized by IR, Raman,¹H-,¹³C-NMR spectroscopy. The Schiff bases were associated with a diversity of inorganic and organic ligands such as chloride, phosphane, arenes, various carbenes (alkylidene, vinylidene, indenylidene and allenylidene as well as N-heterocyclic carbenes) and cyclodienes. By choosing a selective range of substituents for the Schiff base, useful physical and chemical properties of the prepared Rucomplexes can be induced. This synthetic approach is promising in creating a valuable and diverse selection of Ru-complexes, valuable for future applications.     

Synthesis, characterization and oxidizing properties of a diorgano tellurone carrying bulky aromatic substituents

Bis(2,4,6-triisopropylphenyl) tellurone (Tip(2)TeO(2)) was prepared, fully characterized by spectroscopic and X-ray crystallographic analyses, as well as theoretical calculations, and found to be an effective oxidizing agent that was capable of converting alcohols into carbonyl compounds under mild reaction conditions.     

One-pot, novel chemical modification of glycidyl methacrylate copolymers with very bulky organosilicon side chain substituents

Glycidyl methacrylate (GM) random copolymers with styrene and methylstyrene (in a 1:1 and 1:3 mole ratio) were synthesized by solution free radical polymerizations at 70 ± 1 °C using α,α′-azoisobutyronitrile as an initiator. The copolymer compositions were obtained using related ¹H NMR spectra and the polydispersity indices of the copolymers determined using gel permeation chromatography (GPC). Both types of polymer could be modified by incorporation of the highly sterically demanding tris(trimethylsilyl)methyl substituent (Me₃Si)₃C-(Tsi = trisyl) through the ring opening reaction of the epoxy groups in copolymers. Chemical modification was determined by ¹H NMR and infrared spectroscopies. The glass transition temperature T_g of all copolymers was determined by differential scanning calorimetry (DSC). The T_g value of the copolymers containing bulky trisyl groups was found to increase with incorporation of trisyl groups in polymer structures. The presence of trisyl groups in the polymer side chain created new macromolecules with novel modified properties and potential use as membranes for fluid separation.     

Molecular design and synthesis of novel side-chain liquid crystalline polymers

Novel side-chain liquid crystalline polymers were synthesized based on the molecular design of the chemical structures of main-chain, spacer, and mesogenic groups. The main-chain structures are polyether, by the cationic ring-opening polymerization of oxetane derivatives, and polydiene, by the radical polymerization of diene derivatives. Some of the polymers from oxetanes with various mesogen and spacer groups show smectic liquid crystalline phase. Both cyano- and fluorine-substituted biphenyls are good mesogenic groups in these liquid crystalline polymers. Polydiene also acts as a novel main-chain to give smectic liquid crystalline state with cyanobiphenyl or fluorobiphenyl as a mesogen. Not only oligomethylene groups but also siloxane and oligo(oxyethylene) groups act as a component of the spacer groups to give liquid crystalline state.     

Dibenzosuberenylidene-ended fluorophores: rapid and efficient synthesis, characterization, and aggregation-induced emissions

A series of pi-conjugated compounds ending with dibenzosuberenylidene were synthesized efficiently. Their luminescence efficiencies were well-tuned by structural modification. Moreover, relative emission intensities were strongly affected by their existing appearances and exhibited aggregation-induced emission (AIE) behavior. Thus, emissions from nanoparticles, films, or powders were found to be more efficient than those from solutions. It demonstrated that these synthesized compounds might be practically used as fluorescent materials for potential optoelectronic applications.