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The Eu2+-doped G-La 2 Si 2 O 7 phosphor was successfully prepared through the high-temperature solid-state reaction method with the aid of AlF 3 flux. The results of Eu L 3 -edge XANES characterization showed that only Eu3+ can be detected in as-received G-La 2 Si 2 O 7 phosphor and that Al 2 O 3 addition leads to a partial reduction of Eu3+ to Eu2+, while complete reduction occurs with AlF 3 addition. The obtained Eu2+-doped G-La 2 Si 2 O 7 phosphor exhibited typical Eu2+ blue-green emission under the near-UV light excitation. The analysis of Fourier transform infrared spectroscopy (FT-IR) and 27Al nuclear magnetic resonance (NMR) results suggests that Al occupies the Si sites and F occupies the O sites. The positive influence of Al–F doping is related to the structure of the produced phosphors, which was analyzed with the aid of first-principles density functional calculations. The results of the theoretical calculations are a good match to the experimental findings. • A novel blue-green emitting phosphor G-La 2 Si 2 O 7 :Eu2+ was synthesized. • With AlF 3 addition, the phosphor has occurred the complete reduction of Eu3+ to Eu2+. • The theoretical calculations are a good explanation to the experimental findings. [ABSTRACT FROM AUTHOR]

Abstract: This Letter reports the evidences for intramolecular six-membered N–H···O hydrogen bonding in N-benzyl benzamides and five-membered N–H···N hydrogen bonding in N-(pyridin-2-ylmethyl) benzamide. Intramolecular six-membered N–H···X (X=O or F) hydrogen bonding in 2-methoxyl- or 2-fluorobenzamides is used to lock the amide proton from forming strong intermolecular N–H···On bonding. As a result, for the first time the new intramolecular hydrogen bonding patterns are observed in the crystal structures of nine amides, whereas the whole molecules give rise to a new class of three-center hydrogen bonding motif. 1H NMR study in chloroform-d also supports that this weak intramolecular hydrogen bonding pattern exists in solution. [Copyright &y& Elsevier]

Abstract: The capacity of sulfur to form intramolecular five- or six-membered S⋯H–N hydrogen bonding in aromatic amides is assessed. The five-membered S⋯H–N hydrogen bonding is observed in crystal structures of five compounds, whereas the six-membered S⋯H–N hydrogen bonding is revealed in crystal structures of three compounds. The trityl group has been used to promote formation of the weak hydrogen bonding because it efficiently inhibits the competition of the intermolecular CH–N hydrogen bonding. (2D) 1H NMR experiments indicate that both patterns also exist in chloroform. [Copyright &y& Elsevier]

A new acylhydrazone fluorescence probe, SPBH, was synthesized from salicylaldehyde and 4-(pyridin-4-yl)benzohydrazide (PBH). SPBH exhibited high selectivity and a sensitive fluorescence response towards Al3+, even in the presence of other competing metal ions in DMF/H2O (1 : 1, v/v) medium. And, the chemosensor can even detect Al3+ in the intracellular region of human non-small cell lung cancer H460 cells. The binding phenomenon of SPBH was investigated by 1H NMR spectroscopy and HR-MS. Mass spectrometry analysis showed a 1 : 1 complex formation of SPBH with Al3+. The Job plot also confirmed its 1 : 1 interaction. This SPBH/Al3+ complex exhibited excellent fluorescence “turn-off” properties towards the F− anion. Thus, SPBH acts as a sequential fluorescence “Off–On–Off” probe. The limits of detection for Al3+ and F− were calculated from the titration curve and found to be 1.1 × 10−7 M and 1.47 × 10−6 M, respectively. [ABSTRACT FROM AUTHOR]

Three new ( 1 – 3 ) and one known ( 4 ) bioactive terpenoids were isolated from the seeds of Silybum marianum based on the investigation to get new NO inhibitors. Their structures were determined by extensive NMR (1D and 2D NMR) and MS spectroscopic data, and the absolute configurations were identified by experimental and calculated ECD spectra. The NO inhibitory activities in murine microglial BV-2 cells and interactions with iNOS protein by molecular docking were evaluated for all compounds. The results showed that these compounds had potent NO inhibitory effects. [ABSTRACT FROM AUTHOR]

Four hydrogen bonded rigid aromatic hydrazide macrocycles, which bear different number of chiral and/or achiral oligo(ethylene glycol) chains, have been synthesized. 1 H NMR, fluorescence, UV–vis absorption, and circular dichroism experiments showed that the three macrocycles bearing chiral side chains gave rise to one-dimensional chiral column aggregates in aqueous solution. Remarkably, the chiral side chains at two different positions induced the helicity chirality in opposite directions. [ABSTRACT FROM AUTHOR]

Abstract: Two new hydrazide-based quadruple hydrogen-bonding motifs are described. Dipodals based on these two motifs are revealed to form supramolecular polymers, which can further aggregate to form vesicles and/or organogels in hydrocarbons. The quadruple hydrogen-bonding motifs are characterized by the X-ray diffraction and (2D) 1H NMR experiments, while the vesicles and organogels are evidenced by SEM, AFM, TEM, and fluorescent microscopy. [Copyright &y& Elsevier]

This paper describes the synthesis and characterization of the first series of hydrogen bonding-driven hydrazide foldamers and their recognition for alkyl saccharides in chloroform. Oligomers 1, 2-4, 5, 6, and 7, which contain one, two, four, six, or twelve repeated dibenzoyl hydrazide residues, respectively, have been prepared. The rigid and planar conformations of 1 and 2 or 4 have been established with X-ray analysis and 1H NMR spectroscopy, whereas the folding and helical conformations of 5-7 have been evidenced by the 1D and 2D 1H NMR and IR spectroscopy and molecular mechanics calculations. Molecular mechanics calculations also revealed that 5, 6, and 7 possess a rigid cavity with size of Ca. 10.6 to 11.1 Å, and half of the carbonyl groups in the folding conformations are orientated inwardly inside the cavity. 1H NMR and CD experiments revealed that 5-7 efficiently complex alkylated mono- and disaccharides 32- 35 in chloroform. The association constants (Kassoc) of the complexes have been determined with the 1H NMR and fluorescent titration methods. The energy-minimized conformation of 6.34 has been obtained with molecular mechanics calculation. The hydrazide-based folding structures described here represent novel examples of hydrogen bonding-driven foldamers that act as artificial receptors for selective molecular recognition. [ABSTRACT FROM AUTHOR]

A series of oligo(quinoxalineethylene)s which exhibit n-type semi-conducting features were synthesized, and adding Ag+to their solutions induced the backbones to adopt coplanar conformations due to Ag+–N coordination. [ABSTRACT FROM AUTHOR]