Thermo‐ and Acid‐Responsive Photochromic Spironaphthoxazine‐Containing Organogelators

A series of photochromic spironaphthoxazine derivatives has been designed, synthesized, and characterized by using ¹H NMR spectroscopy, FAB mass spectrometry, and elemental analysis. Their photophysical and photochromic behavior have been investigated. Two of the compounds (G¹²‐en‐SA‐SO and G¹⁶‐en‐SA‐SO) have been shown to be capable of forming stable thermoreversible organogels in organic solvents, tested by the “stable‐to‐inversion of a test tube” method. Addition of p‐toluenesulfonic acid was found to induce the formation of stable organogels at concentrations below that of the critical gelation concentration (c.g.c.), with a concomitant change in color from colorless to purple. Transmission electron microscopy and scanning electron microscopy of the xerogels showed typical fibrous structures in the micrometer scale. The activation parameters for the bleaching reaction of G⁸‐en‐SA‐SO in the solution state and G¹⁶‐en‐SA‐SO in the gel state have been determined in ethanol through kinetic studies at various temperatures. The results showed that the rate of the bleaching reaction in the gel state was much slower than that in the solution state.     

Capping nanoparticles with graphene quantum dots for enhanced thermoelectric performance

Graphene quantum dots (GQDs) are shown to serve as phase transfer agents to transfer various types of nanoparticles (NPs) from non-polar to polar solvents. Thorough characterization of the NPs proves complete native ligand exchange. Pellets of this GQD–NP composite show that the GQDs limit the crystal size during spark plasma sintering, yielding enhanced thermoelectric performance compared with NPs exchanged with inorganic ions. A photoluminescence study of the GQD–NP composite also suggests energy transfer from GQDs to NPs.     

Selective surface reactions for Janus ORMOSIL particles with multiple functional groups using an ordered monolayer film at liquid-liquid interface

Monodispersed, submicron-sized Janus ORMOSIL particles with multiple functional groups were prepared by the selective surface reaction of a monolayer film formed at a hexane-water interface. A well-ordered monolayer film was obtained by self-assembly of ORMOSIL particles with multiple functional groups at hexane-water interface. The photopolymerization of an ordered monolayer containing ORMOSIL particles yields a rigid film strong enough to maintain its integrity for transfer and further chemical reaction. The chemical reaction of this ordered film with organic and inorganic functional groups produced Janus ORMOSIL particles with multiple functional groups. The morphologies, structures, and chemical compositions of monolayer films and Janus ORMOSIL particles were characterized by FT-IR, solid state NMR, X-ray diffraction (XRD), optical microscopy (OM), electron microscopies (SEM and TEM), and confocal laser scanning microscopy.     

含三氟乙酰苯基喹啉配体的铱配合物的合成及其电致发光性能

通过2-(4'-三氟乙酰苯基)-4-苯基喹啉(tfapqH)与三氯化铱反应生成了二氯桥中间体,然后用吡啶-2-甲酸(picH)解离得到双环金属铱配合物Ir(tfapq)₂pic。Ir(tfapq)₂pic在二氯甲烷中的发光波长为584 nm,量子产率约为0.846,磷光寿命为1.211 μs,比没有三氟乙酰修饰的铱配合物波长蓝移的10 nm,量子效率提高了约5%,磷光寿命降低了0.286 μs,辐射跃迁加快,半波宽度降低了约26%,色纯度提高。其HOMO能级为-5.405 eV,LUMO能级为-3.277 eV,能级相对于未修饰的配合物都有所降低,且HOMO降低更明显,总的效果是能级差增加。Ir(tfapq)₂pic 10%的热失重温度为301 ℃,比未修饰铱配合高近50 ℃。当Ir(tfapq)₂pic以2%质量浓度掺杂于PVK-PBD中做成电致发光器件时的效率最高,电致发光波长为594 nm。器件的启明电压为7.3 V,最大亮度为8 571 cd·m^-2,最大外量子效率为12.65%,对应的流明效率为22.14 cd·A^-1。色坐标是(0.58,0.40)。     

One-step synthesis of large-aspect-ratio single-crystalline gold nanorods by using CTPAB and CTBAB surfactants

Gold nanorods were prepared in high yields by using a one-step seed-mediated process in aqueous cetyltripropylammonium bromide (CTPAB) and cetyltributylammonium bromide (CTBAB) solutions in the presence of silver nitrate. The diameters of the nanorods range from 3 to 11 nm, their lengths are in the range of 15 to 350 nm, and their aspect ratios are in the range of 2 to 70. The diameters of the Au nanorods obtained from one growth batch in CTPAB solutions decrease as their lengths increase, and their volumes decrease as the aspect ratios increase. The diameters of the Au nanorods obtained from one growth batch in CTBAB solutions first decrease and then slightly increase as their lengths increase, and their volumes increase as the aspect ratios increase. These Au nanorods are single-crystalline and are seen to be oriented in either the [100] or [110] direction under transmission electron microscopy imaging, irrespective of their sizes. To the best of our knowledge, this is the first report of the preparation by using wet-chemistry methods of single-crystalline Au nanorods with aspect ratios larger than 15.     

Nickel(II) complexes of bidentate N-heterocyclic carbene/phosphine ligands: efficient catalysts for Suzuki coupling of aryl chlorides

Nickel(II) complexes of bidentate N-heterocyclic carbene (NHC)/phosphane ligand L were prepared and structurally characterized. Unlike palladium, which forms [PdCl(2)(L)], the stable nickel product isolated is the ionic [Ni(L)(2)]Cl(2). These Ni(II) complexes are highly robust in air. Among different N-substituents on the ligand framework, the nickel complex of ligand L bearing N-1-naphthylmethyl groups (2 a) is a highly effective catalyst for Suzuki cross-coupling between phenylboronic acid and a range of aryl halides, including unreactive aryl chlorides. The activities of 2 a are largely superior to those of other reported nickel NHC complexes and their palladium counterparts. Unlike the previously reported [NiCl(2)(dppe)] (dppe=1,2-bis(diphenylphosphino)ethane), 2 a can effectively catalyze the cross-coupling reaction without the need for a catalytic amount of PPh(3), and this suggests that the PPh(2) functionality of hybrid NHC ligand L can partially take on the role of free PPh(3). However, for unreactive aryl chlorides at low catalyst loading, the presence of PPh(3) accelerates the reaction.     

Palladium complexes with ethylene-bridged bis(N-heterocyclic carbene) for C-C coupling reactions

A series of new ethylene-bridged bis(imidazolium) halides with various N-substitutions were synthesized. Complexation of these imidazolium halides with Pd(OAc)₂ produced new Pd(II) ethylene-bridged bis(carbene) complexes. Crystallographic analyses of some of the new imidazolium salts and Pd(II) complexes were determined. Applications of these seven-member palladacycles in Suzuki and Heck coupling reactions produced comparable catalytic activities to those of six-member analogs.     

Design, synthesis, characterization, luminescence and non-linear optical (NLO) properties of multinuclear platinum(II) alkynyl complexes

A series of luminescent multinuclear platinum(II) alkynyl complexes containing triethynylbenzene or 1,4-bis(3,5-diethynylphenyl)buta-1,3-diyne as cores has been successfully synthesized and characterized. The electronic absorption, emission, nanosecond transient absorption and electrochemical properties of these complexes have been reported. These complexes show long-lived emissions in degassed benzene solution and in alcoholic glass at 77 K. Moreover, they are found to exhibit two-photon absorption (2PA) and two-photon induced luminescence (TPIL) properties, and their two-photon absorption cross-sections have been determined to be 6-191 GM upon excitation at 720 nm. Through a systematic comparison, it has been found that tetra- and hexanuclear platinum(II) complexes show better 2PA and TPIL properties than their di- and trinuclear counterparts.     

反相悬浮聚合法制备球状卡波树脂的研究

以偶氮二异丁脒盐酸盐(V50)作为引发剂,失水山梨醇硬脂酸酯(Span60)和聚二甲基硅氧烷PEG-7磷酸酯为复合分散剂,蔗糖烯丙基醚和三甲基丙基聚氧乙烯(15)醚三丙烯酸酯为复合交联剂,丙烯酸为单体,正已烷为反应介质,采用反相悬浮聚合方法制备了球状卡波树脂.用光学显微镜和扫描电镜分别对聚合反应的成粒过程和产物的形貌进行了研究.结果表明,聚合体系呈现典型的悬浮聚合相态特征,并获得了堆积密度较高(0.65 g/cm3)的球状卡波树脂.聚合反应动力学研究结果表明,该反相悬浮聚合的聚合速率对单体浓度和引发剂浓度的反应级数分别约为1.36和0.70;聚合反应的表观活化能为78.0 kJ/mol.交联剂对卡波树脂的性能有重要的影响,通过适度交联可提高产物的增稠效率及其抗剪切性能.