A new fluorescent chemosensor for fluoride anion based on a pyrrole-isoxazole derivative.

Molecules containing polarized NH fragments that behave as anion-binding motifs are widely used as receptors for recognition and sensing purposes in aprotic solvents. We present here a new example of a receptor, 3-amino-5-(4,5,6,7-tetrahydro-1H-indol-2-yl)isoxazole-4-carboxamide (receptor 1), which contains pyrrole, amide and amino subunits. This receptor shows both changes in its UV-vis absorption and fluorescence emission spectra upon the addition of F(-), resulting in highly selectivity for fluoride detection over other anions, such as Cl(-), Br(-), I(-), HSO(4) (-), H(2)PO(4) (-) and AcO(-) in CH(3)CN. (1)H NMR titration, time-dependent density functional theory (TDDFT) calculations and other experiments confirm that the sensing process is brought about by deprotonation of the pyrrole-NH in receptor 1.

Exploring intertrimer Cu...Cu interactions and further phosphorescent properties of aryl trimer copper(I) Pyrazolates via substituent changing and external pressure.

To explore the effect of intertrimer Cu...Cu interactions on the phosphorescent properties of trimeric copper(I) pyrazolates, three new complexes with identical core cluster structures and different substituents, {[3,5-(Me)(2)-4-(Ph)Pz]Cu}(3) (MPC-P), {[3,5-(Me)(2)-4-(1-Naph)Pz]Cu}(3) (MPC-N), and {[3,5-(Me)(2)-4-(9-Anthr)Pz]Cu}(3) (MPC-A), were synthesized. The intertrimer Cu...Cu distances of the three complexes were obtained from X-ray crystallographic data or molecular dynamics simulations. The phosphorescent properties of the three complexes were investigated at various pressures. At ambient pressure, the emissions of the three complexes were dramatically different from each other. For MPC-P, the main emission band was identified as phosphorescence and MPC-N gave a predominant emission of fluorescence and a weak emission of phosphorescence. When the substitutent was replaced by an anthryl group in MPC-A, no phosphorescence was observed, except for a strong fluorescence band. The phosphorescence of the trimer copper(I) pyrazolates was assigned to the excited-state dimer/polymer *[Cu(3)](n) with LMCT characteristics. Under higher external pressures, only phosphorescent intensities of MPC-P showed considerable enhancement at pressures up to 2 GPa. External pressure reduced the intertrimer Cu...Cu distances of MPC-P and enhanced the phosphorescence intensities, providing a direct evidence to support the assignment of phosphorescence.