Selective fluorescence sensor based on ion-imprinted polymer-modified quantum dots for trace detection of Cr(VI) in aqueous solution.

A new fluorescence sensor (QDs-IIP), based on ion-imprinted polymers (IIP) as recognition element and Mn-doped ZnS quantum dots (QDs) as fluorophore, was synthesized for the selective and sensitive determination of hexavalent chromium (Cr(VI)) ions. The QD was first coated by SiO layer, and then modified with Cr(VI)-imprinted polymer. Several parameters affecting fluorescence intensity such as tetraethylorthosilicate (TEOS) volume, ZnS:Mn@SiO amount, and radiation time were investigated and optimized.

Determination of dopamine hydrochloride by host-guest interaction based on water-soluble pillar[5]arene.

The supramolecular interaction between the water-soluble pillar[5]arene (WP[5]) as host and dopamine hydrochloride (DH) as guest was studied by spectrofluorometry. The fluorescence intensity of DH gradually decreased with increasing WP[5] concentration, and the possible interaction mechanism between WP[5] and DH was confirmed by H NMR, 2D NOESY, and molecular modelling. Based on significant DH fluorescence, a highly sensitive and selective method for DH determination was developed for the first time.

The mechanisms for N-heterocyclic olefin-catalyzed formation of cyclic carbonate from CO2 and propargylic alcohols.

The mechanistic details of N-heterocyclic olefin-catalyzed formation of cyclic carbonate from CO2 and propargylic alcohols were investigated by DFT calculations. Six mechanisms, four for the formation of five-membered cyclic carbonate (M-A, M-B, M-B' and M-C), and two for six-membered cyclic carbonate (M-D and M-E), were fully investigated. The energy profiles in dichloromethane showed that M-B is the predominant reaction with the lowest barrier of 31.

N,N'-Bis(4-nitro-phen-yl)biphenyl-2,2'-dicarboxamide.

In the title compound, C(26)H(18)N(4)O(6), the amide units are approximately coplanar with the benzene ring bonded to the N atom [dihedral angles of 10.59 (10) and 24.00 (12)°], but twisted significantly out of the plane of the benzene ring bonded to the carbonyl C atom [dihedral angles of 57.

N,N'-Bis(2-methoxy-phen-yl)biphenyl-2,2'-dicarboxamide.

In the title compound, C(28)H(24)N(2)O(4), the dihedral angle between the two rings of the biphenyl unit is 75.34 (9)°. The outer aromatic rings form dihedral angles of 66.

9,10-Bis{2-[1-(2-pyridylmeth-yl)imidazolium-3-yl]eth-oxy}anthracene bis(hexa-fluoridophosphate).

The cation of the title compound, C(36)H(34)N(6)O(2) (2+)·2PF(6) (-), lies across a crystallographic inversion centre. The imidazole and pyridine rings form dihedral angles of 82.28 (5)° and 11.