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The formation of radiative exciplexes of a series of electron donor-acceptor pairs of 1,2,4,5-tetracyanobenzene (TCB) and bulky alkyl-substituted benzenes is reported for the first time in nonpopular solvents BEN, TOL, and PXY. Exciplexes of donor-acceptor pairs of bulky and flat donors with similar structures and electron-transfer properties give almost the same fluorescence quantum yields.

The article explains the synthesis, as well as the properties of a ratiometric fluorescent chemodosimeter, which is shown to contain a guanidiniocarbonylpyrrole and a 9-(aminomethyl)anthracene moiety. The selective recognition of the compound for sulfite in the aqueous solution is also discussed.

Several techniques are employed to study the photoresponsive J-aggregation behavior of a novel azobenzene-phthalocyanine dyad. The dyad is shown to exhibit third-order optical nonlinearity and hence can be easily used in the field of nonlinear optics applications.

A series of nonlinear optical (NLO) chromophores are prepared, in which pyrrole moieties are the conjugated bridge. These chromophores have shown similar or enhanced NLO effects and optical behavior when compared to their analogues containing furan or thiophene groups as the bridge.

Transient diffractive holography is seen for the green (GPR) and blue (BPR) absorbing proteorhodopsins. Four types of PR are evaluated, including the wild-type green and blue proteins and their long M-state variants, GPR E108Q and BPR E110Q.

The hybrid perovskites with special optoelectronic properties have attracted more attention to the scientific and industrial applications. However, because of the toxicity and instability of lead complexes, there is interest in finding a nontoxic substitute for the lead in the halides perovskites and solving the ambiguous crystal structures and phase transition of NH(CH3)3SnX3 (X = Cl, Br). Here, we report the bulk crystal growths and different crystal morphologies of orthorhombic hybrid perovskites NH(CH3)3SnX3 (X = Cl, Br) in an ambient atmosphere by bottom-seeded solution growth (BSSG) method. More importantly, detailed structural determination and refinements, phase transition, band gap, band structure calculations, nonlinear optical (NLO) properties, XPS, thermal properties, and stability of NH(CH3)3SnX3 (X = Cl, Br) single crystals are demonstrated. NH(CH3)3SnCl3 single crystal undergoes reversible structural transformation from orthorhombic space group Cmc 21 (no. 36) to monoclinic space group Cc (no. 9) and NH(CH3)3SnBr3 belongs to the orthorhombic space group Pna 21 (no. 33) by DSC, single-crystal X-ray diffraction and temperature-dependent SHG measurements, which clarify the former results. These results should pave the way for further studies of these materials in optoelectronics. [ABSTRACT FROM AUTHOR]

An intramolecular aza-Michael reaction with a Cbz carbamate and an enone is reported to result in 3,5-disubstituted nitrogen-containing heterocycles. Either cisor transisomers were obtained selectively using chiral substrates and an achiral Pd (II) complex or strong Brønsted acid catalysis. A range of substrates undergoes these selective transformations. Functionalization of the resulting products yielding bicyclic heterocycles is also demonstrated. [ABSTRACT FROM AUTHOR]

When using tetrachloromethane as the reagent gas in gas chromatography-ion trap mass spectrometry equipped with hybrid ionization source, the cation CCl was generated in high abundance and further gas-phase experiments showed that such an electron-deficient reagent ion CCl could undergo interesting ion-molecule reactions with various volatile organic compounds, which not only present some informative gas-phase reactions, but also facilitate qualitative analysis of diverse volatile compounds by providing unique mass spectral data that are characteristic of particular chemical structures. The ion-molecule reactions of the reagent ion CCl with different types of compounds were studied, and results showed that such reactions could give rise to structurally diagnostic ions, such as [M + CCl - HCl] for aromatic hydrocarbons, [M - OH] for saturated cyclic ether, ketone, and alcoholic compounds, [M - H] ion for monoterpenes, M for sesquiterpenes, [M - CHCO] for esters, as well as the further fragment ions. The mechanisms of ion-molecule reactions of aromatic hydrocarbons, aliphatic ketones and alcoholic compounds with the reagent ion CCl were investigated and proposed according to the information provided by MS/MS experiments and theoretical calculations. Then, this method was applied to study volatile organic compounds in Dendranthema indicum var. aromaticum and 20 compounds, including monoterpenes and their oxygen-containing derivatives, aromatic hydrocarbon and sesquiterpenes were identified using such ion-molecule reactions. This study offers a perspective and an alternative tool for the analysis and identification of various volatile compounds. [ABSTRACT FROM AUTHOR]

Three isomeric fluorescent β-cyclodextrins bearing 2-, 3-, and 4-(2-aminoethyl)amino-N-butylbenzamide, respectively (1-3) have been synthesized. The conformations of these fluorescent CDs have been investigated by 2D NMR and induced circular dichromism. It is confirmed that the ortho isomer 1 takes a butyl-included conformation, while the other two isomers 2 and 3 display a phenyl-included conformation, respectively. The three fluorescent CDs 1-3 exhibited totally different self- and guest-inclusion fluorescence behavior. In the presence of adamantane carboxylate sodium (ADA) or deoxycholate sodium (DCA), the fluorescence intensity of 1 showed an enhancement over 1-fold, while 2 exhibited dramatic fluorescence quenching. Interestingly, the fluorescent responses of 3 toward two guests respectively were highly distinguishable. The fluorescence intensity of 3 only showed a slight increase upon the addition of ADA, but the addition of DCA led to a large decrease in fluorescence intensity. The investigations have been further carried out by 2D NMR, induced circular dichromism, fluorescence spectroscopy and molecular modeling to explore the relationships between the conformations and the fluorescence characteristics of CDs 1-3 in the absence and presence of guest molecules. On the basis of the above investigations, the origins for the different fluorescence behaviors have been proposed. [ABSTRACT FROM AUTHOR]

A highly efficient one-pot synthesis of substituted piperidines was developed through nitroalkene, amine, and enone condensation. The transformation was suitable for a large group of substrates, giving excellent yields and diastereoselectivity. Reactions using chiral amines revealed a chirality induction through the unusual exocyclic stereochemistry control, producing enantiomeric pure piperidines in simple steps. [ABSTRACT FROM AUTHOR]

With the development of ultrafast optics, all-optical control of terahertz wave modulation based on semiconductors has become an important technology of terahertz wave regulation. In this article, an ultrawideband terahertz linear polarization converter consisting of a double-layered metasurface is first proposed. The polarization conversion ratio of the device is ∼ 100% at 0.2-2.2 THz, and the transmission of copolarization approaches zero in the full band, which demonstrates the ability of high-purity output with rotating input linear polarization of 90° over an ultrawideband. By analysis of the surface current and electric field distribution, the physical mechanism of polarization conversion is elucidated. In addition, the influence of important geometric parameters on the device is discussed and analyzed in detail, which provides theoretical support for the design of high-performance polarization converters. More importantly, by introducing semiconductor silicon to construct an actively controllable metasurface, we design all-optical polarization converters based on a meta-atomic molecularization metasurface and all-dielectric metasurface; the dynamically tunable ultrawideband linear polarization conversion is realized under optical pumping, which solves the inherent problem of the performance of the metasurface polarization converters. Numerical simulation shows that the switching response of the two types of actively controllable devices under optical pumping is about 700 and 1800 ps, respectively, and can manipulate polarized wave conversion ultrafast, which brings new opportunities for all-optical controlled ultrafast terahertz polarization converters. Our results provide a feasible scheme for the development of state-of-the-art active and controllable ultrafast terahertz metasurface polarization converters, which have great application potential in short-range wireless terahertz communication, ultrafast optical switches, the transient spectrum, and optical polarization control devices., Competing Interests: The authors declare no competing financial interest., (© 2023 The Authors. Published by American Chemical Society.)

In this paper, we analyze the thermodynamics of interactions between surfaces mediated by polymer-tethered ligand-receptor binding. From statistical thermodynamics calculations, we obtain an effective two-dimensional binding constant reflecting contributions from the microscopic binding affinity as well as from the conformation entropy of the polymer tethers. The total interaction is a result of the interplay between attractive binding and repulsion due to confinement of the polymer chains. We illustrate the differences between three scenarios when the binding molecules are (1) immobile, (2) mobile with a fixed density, and (3) mobile with a fixed chemical potential (connected to a reservoir), which correspond to different biological or experimental situations. The key features of interactions, including the range of adhesion (onset of binding) and the equilibrium separation, can be obtained from scaling analysis and are verified by numerical solutions. In addition, we also extend our method of treating the quenched case with immobile ligands and receptors developed in a previous paper [Martin, J. I.; Zhang, C.-Z.; Wang, Z.-G. J. Polym. Sci., Part B: Polym. Phys. 2006, 44, 2621-2637] as a density expansion in terms of both ligand and receptor densities. Finally, we examine several cases having ligand-receptor pairs with different tether lengths and binding affinities, and/or nonbinding linear polymers as steric repellers. Such systems can exhibit complex interactions such as a double-well potential, or a bound state with an adjustable barrier (due to the repellers), which have both biological and bioengineering relevance.