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991.
Samadhan S. Nagane Sachin S. Kuhire Uday A. Jadhav Sushilkumar A. Dhanmane Prakash P. Wadgaonkar 《Journal of polymer science. Part A, Polymer chemistry》2019,57(5):630-640
A bisphenol bearing pendant maleimide group, namely, N‐maleimidoethyl‐3, 3‐bis(4‐hydroxyphenyl)‐1‐isobenzopyrrolidone (PPH‐MA) was synthesized starting from phenolphthalein. Aromatic (co)polyesters bearing pendant maleimide groups were synthesized from PPH‐MA and aromatic diacid chlorides, namely, isophthaloyl chloride (IPC), terephthaloyl chloride (TPC), and 50:50 mol % mixture of IPC and TPC by low temperature solution polycondensation technique. Copolyesters were also synthesized by polycondensation of different molar proportions of PPH‐MA and bisphenol A with IPC. Inherent viscosities and number‐average molecular weights of aromatic (co)polyesters were in the range of 0.52–0.97 dL/g and 20,200–32,800 g/mol, respectively indicating formation of medium to reasonably high‐molecular‐weight polymers. 13C NMR spectral analysis of copolyesters revealed the formation of random copolymers. The 10% weight loss temperature of (co)polyesters was found in the range 470–484 °C, indicating their good thermal stability. A selected aromatic polyester bearing pendant maleimide groups was chemically modified via thiol‐maleimide Michael addition reaction with two representative thiol compounds, namely, 4‐chlorothiophenol and 1‐adamantanethiol to yield post‐modified polymers in a quantitative manner. Additionally, it was demonstrated that polyester containing pendant maleimide groups could be used to form insoluble crosslinked gel in the presence of a multifunctional thiol crosslinker. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 630–640 相似文献
992.
A series of dinuclear cycloplatinated(II) complexes with general closed formula of [Pt2Me2(C^N)2(μ‐P^P)] (C^N = 2‐vinylpyridine (Vpy), 2,2′‐bipyridine N‐oxide (O‐bpy), 2‐(2,4‐difluorophenyl)pyridine (dfppy); P^P = 1,1‐bis(diphenylphosphino)methane (dppm), N,N‐bis(diphenylphosphino)amine (dppa)) are reported. The complexes were characterized by means of NMR spectroscopy. Due to the presence of dppm and dppa with short backbones as bridging ligands, two platinum centres are located in front of each other in these complexes so a Pt…Pt interaction is established. Because of this Pt…Pt interaction, the complexes have bright orange colour under ambient light and are able to strongly emit red light under UV light exposure. These strong red emissions originate from a 3MMLCT (metal–metal‐to‐ligand charge transfer) electronic transition. In most of these complexes, the emissions have unstructured bell‐shaped bands, confirming the presence of large amount of 3MMLCT character in the emissive state. Only the complexes bearing dfppy and dppa ligands reveal dual luminescence: a high‐energy structured emission originating from 3ILCT/3MLCT (intra‐ligand charge transfer/metal‐to‐ligand charge transfer) and an unstructured low‐energy band associated with 3MMLCT. In order to describe the nature of the electronic transitions, density functional theory calculations were performed for all the complexes. 相似文献
993.
Gogoi Deepshikha Hussain Amreen A. Pal Arup R. 《Plasma Chemistry and Plasma Processing》2019,39(1):277-292
Plasma Chemistry and Plasma Processing - We report plasma based fabrication of an optoelectronic device with plasmon enhanced infrared sensitivity realized by integrating plasmonic gold... 相似文献
994.
Dr. Tatsuya Nishimaru Dr. Kohei Eto Dr. Keita Komine Prof. Dr. Jun Ishihara Prof. Dr. Susumi Hatakeyama 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(33):7927-7934
The first total synthesis of lajollamycin B, a structurally novel nitro-tetraene spiro-β-lactone/γ-lactone antibiotic, is described. The convergent synthesis involves the construction of the C8′–C11′ nitrodienylstannane and its coupling with the segment prepared from the C1′–C7′ ω-iodoheptadienoic acid and the right-hand heterocyclic fragment, which has been utilized for our previous syntheses of oxazolomycin A. The revision of the geometry of the terminal Δ10′, 11′-double bond from E to Z is also described for the structure of natural lajollamycin B. 相似文献
995.
Dr. Stepas Toliautas Dr. Jelena Dodonova Audrius Žvirblis Ignas Čiplys Artūras Polita Dr. Andrius Devižis Prof. Sigitas Tumkevičius Prof. Juozas Šulskus Dr. Aurimas Vyšniauskas 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(44):10342-10349
Molecular rotors are a class of fluorophores that enable convenient imaging of viscosity inside microscopic samples such as lipid vesicles or live cells. Currently, rotor compounds containing a boron-dipyrromethene (BODIPY) group are among the most promising viscosity probes. In this work, it is reported that by adding heavy-electron-withdrawing −NO2 groups, the viscosity-sensitive range of a BODIPY probe is drastically expanded from 5–1500 cP to 0.5–50 000 cP. The improved range makes it, to our knowledge, the first hydrophobic molecular rotor applicable not only at moderate viscosities but also for viscosity measurements in highly viscous samples. Furthermore, the photophysical mechanism of the BODIPY molecular rotors under study has been determined by performing quantum chemical calculations and transient absorption experiments. This mechanism demonstrates how BODIPY molecular rotors work in general, why the −NO2 group causes such an improvement, and why BODIPY molecular rotors suffer from undesirable sensitivity to temperature. Overall, besides reporting a viscosity probe with remarkable properties, the results obtained expand the general understanding of molecular rotors and show a way to use the knowledge of their molecular action mechanism for augmenting their viscosity-sensing properties. 相似文献
996.
Oliver Back Dr. Christoph Förster Prof. Dr. Thomas Basché Prof. Dr. Katja Heinze 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(26):6542-6552
2-Iminopyrroles [HtBuL, 4-tert-butyl phenyl(pyrrol-2-ylmethylene)amine] are non-fluorescent π systems. However, they display blue fluorescence after deprotonation with alkali metal bases in the solid state and in solution at room temperature. In the solid state, the alkali metal 2-imino pyrrolates, M(tBuL), aggregate to dimers, [M(tBuL)(NCR)]2 (M=Li, R=CH3, CH(CH3)CNH2), or polymers, [M(tBuL)]n (M=Na, K). In solution (solv=CH3CN, DMSO, THF, and toluene), solvated, uncharged monomeric species M(tBuL)(solv)m with N,N′-chelated alkali metal ions are present. Due to the electron-rich pyrrolate and the electron-poor arylimino moiety, the M(tBuL) chromophore possesses a low-energy intraligand charge-transfer (ILCT) excited state. The chelated alkali cations rigidify the chromophore, restricting intramolecular motions (RIM) by the chelation-enhanced fluorescence (CHEF) effect in solution and, consequently, switch-on a blue fluorescence emission. 相似文献
997.
Prof. Shinji Toyota Dr. Eiji Tsurumaki 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(28):6878-6890
Saturn-like systems consisting of nanoscale rings and spheres are fascinating motifs in supramolecular chemistry. Several ring molecules are known to include spherical molecules at the center of the cavity via noncovalent attractive interactions. In this Minireview, we generalize the molecular design, the structural features, and the supramolecular chemistry of such “nano-Saturns”, which consist of monocyclic rings and fullerene spheres (mainly C60), on the basis of previous experimental and theoretical studies. Ring molecules are classified into three types (loop, belt, and disk) according to their shapes and possible interactions. Whereas typical belt-shaped rings tend to form tight complexes due to the wide contact area via π–π interactions, flat disk-shaped rings generally form weak complexes due to the narrow contact area mainly via CH–π interactions. In spite of the small association energies, disk-shaped rings are attractive because such rings can mimic the planet Saturn precisely as exemplified by an anthracene cyclic hexamer–C60 complex. 相似文献
998.
Optics and Spectroscopy - Experiments carried out in recent years using single-molecule spectroscopy to study the low-temperature dynamics of some molecular solid-state media with a disordered... 相似文献
999.
It is proved that, for some initial data, the solutions of the Cauchy problem for the cubic Schrödinger evolution equation blow up in finite time whose exact value is estimated from above. In addition, lower bounds for the blow-up rate of the solution in certain norms are obtained.
相似文献1000.
Mathematical Notes - A two-coloring is said to be equitable if, on the one hand, there are no monochromatic edges (the coloring is regular) and, on the other hand, the cardinalities of color... 相似文献