Novel selective and sensitive optical chemosensor based on phenylfluorone derivative for detection of Ge(IV) ion in aqueous solution.

A water soluble chemosensor for Ge4+ ion based on fluorone derivative containing 3,4-bis(2-(diethylamino)-2-oxoethoxy)phenyl (R8) has been synthesized. The binding abilities between R8 and 10 equiv. of Na+, K+, Ca2+, Fe2+, Cu2+, Cd2+, Hg2+, Pb2+, Al3+, Cr3+, Fe3+ and Ge4+ ions in 1% v/v EtOH-water (tris-buffer pH 7.0) were studied using UV-vis and fluorescence spectrophotometry. When observed by naked-eyes, the color of R8 changed from yellow-orange to pink and the fluorescent color changed from green to non-fluorescence when complexed with Ge4+ ion. The spectral analysis showed that UV-vis absorption and fluorescence emission intensity of R8 decreased dramatically when Ge4+ ion was added comparing with other ions. To explain this behavior, the quantum calculation was performed using the hybrid density functional at B3LYP /LanL2DZ level of theory. The calculated orbital energies indicated that the decreasing of UV-vis absorption and the quenching of fluorescence were due to the complexation induced metal to ligand charge transfer. The association constants (Ka) of R8-Ge4+ complexes calculated from Benesi-Hildebrand equation was 6.21 × 105 M-1. The UV-vis detection limit for Ge4+ was 4.40 × 10-7 M which was three orders of magnitude lower than those of Al3+, Cd2+, Cu2+ and Na+ ion.

Optical chemosensors for Cu(II) ion based on BODIPY derivatives: an experimental and theoretical study.

Two BODIPY derivatives for Cu(2+) ion chemosensors containing 4-[2-(diethylamino)-2-oxoethoxy]phenyl (BDP1) and 3,4-bis[2-(diethylamino)-2-oxoethoxy]phenyl (BDP2) were synthesized by coupling appropriate N,N-diethyl-2-(4-formylphenoxy)acetamide and 2,4-dimethylpyrrole moieties in the presence of trifluoroacetic acid and anhydrous dichloromethane at room temperature. The binding abilities between these chemosensors and 50 equivalents of Na(+), K(+), Ag(+), Ca(2+), Fe(2+), Ni(2+), Cu(2+), Zn(2+), Cd(2+), Hg(2+) and Pb(2+) ions were studied using UV-vis and fluorescence spectrophotometry. The results show that, compared to other ions, both the UV-vis absorption and fluorescence emission intensity of BDP2 decreased dramatically when Cu(2+) ion was added. To explain this behavior, ab initio quantum chemical calculations were performed using correlated second-order Møller-Plesset perturbation theory (MP2/LanL2DZ). The calculated orbital energies indicated that the decrease in UV-vis absorption intensity and the quenching of fluorescene emission were due to the single-electron reduction of Cu(2+) to Cu(+) ion.

Density functional investigation of hydrogen gas adsorption on Fe-doped pristine and Stone-Wales defected single-walled carbon nanotubes.

The adsorptions of hydrogen molecule of the Fe - doped pristine and Stone - Wales defected armchair (5,5) single - walled carbon nanotubes (SWCNTs) compared with the pristine SWCNT were investigated by using the density functional theory at the B3LYP/LanL2DZ level. The doping of Fe atom into SWCNTs occurring via an exothermic process was found. The adsorptions of hydrogen molecule on the Fe - doped structures of either perfect or SW defected SWCNTs are stronger than on their corresponding undoped structures. The structural and electronic properties of the pristine and SW defected SWCNTs, their Fe - doped structures and their hydrogen molecule adsorptions are reported.

Gas adsorption on the Zn-, Pd- and Os-doped armchair (5,5) single-walled carbon nanotubes.

The adsorption of NO(2), NH(3), H(2)O, CO(2) and H(2) gases on the undoped, Zn-, Pd- and Os-doped armchair (5,5) single-walled carbon nanotubes (SWCNTs) were studied using density functional method. The adsorptions of these five gases on the Zn-, Pd- and Os-doped SWCNTs are obviously stronger than on the undoped SWCNT and their adsorption abilities are in the same order: NO(2) > NH(3) > H(2)O > CO(2) > H(2). Adsorption energies for all the studied gases on the undoped, Zn-, Pd- and Os-doped SWCNTs computed at the B3LYP/LanL2DZ level are reported.

Design and synthesis of thiourea based receptor containing naphthalene as oxalate selective sensor.

The thiourea based receptor containing naphthalene groups (1), has been successfully designed and synthesized for application as an oxalate receptor. A density functional theory at B3LYP/6-31G(d,p) level of theory has been applied to predict the binding ability between 1 and selected anions, i.e., oxalate, malonate, succinate, glutarate, dihydrogen phosphate, and hydrogen sulphate. Calculation results point out that receptor 1 shows the strongest interaction to oxalate ion with the binding free energy of 172.48 kcal mol(-1). The recognition ability of 1 to the selected anions has been also investigated by means of the absorption and emission techniques. Experimental results are in excellent agreement with the calculation data in which receptor 1 shows highly selective for oxalate ion over the other anions with logbeta of 3.82 (0.02) M(-1) by means of the size of binding cavity.