A rhodamine derivative as selective fluorescent and colorimetric chemosensor for mercury (II) in buffer solution, test strips and living cells.

In this paper, we reported a new rhodamine derivative bearing 2,4-dichloroquinazoline as a selective fluorescent chemosensor for Hg(2+). The ring-opening process of spirolactam enabled the large fluorescent enhancement and colorimetric change by Hg(2+) induced configuration transformation of the rhodamine. Moreover, the fluorescence changes of the chemosensor were dramatically specific for Hg(2+) in the presence of other metal ions, which could meet the selective requirements for practical application. Under optimized experimental conditions, the linear response range covered the concentration range of Hg(2+) from 0 to 1.0×10(-6)M, and the limit of detection was calculated to be 2.7×10(-8)M. In addition, the probe was also successfully applied to the determination of Hg(2+) in water samples, test strips and living cells.

2-Chloro-quinazolin-4(3H)-one.

In the title compound, C(8)H(5)ClN(2)O, the quinazoline system is approximately planar with a maximum deviation from the least-squares plane of 0.034 (2) Å. In the crystal, classical N-H⋯O and weak non-classical C-H⋯N hydrogen bonds link the mol-ecules.

3-[(E)-2-Chloro-3,3,3-trifluoro-prop-1-en-1-yl]-N-(2-fluoro-phen-yl)-2,2-dimethyl-cyclo-propane-1-carboxamide.

The phenyl ring in the title compound, C(15)H(14)ClF(4)NO, makes a dihedral angle of 80.3 (3)° with the cyclo-propane ring. In the crystal, mol-ecules are linked by N-H⋯O hydrogen bonds into chains running along the a axis.

3-[(E)-2-Chloro-3,3,3-trifluoro-prop-1-en-1-yl]-N-(2-chloro-phen-yl)-2,2-dimethyl-cyclo-propane-1-carboxamide.

In the title compound, C(15)H(14)Cl(2)F(3)NO, synthesized by the reaction of 3-[(E)-2-chloro-3,3,3-trifluoro-prop-1-en-yl]-2,2-dimethyl-cyclo-propane-carb-oxy-lic acid and 2-chloro-aniline, the aromatic ring makes a dihedral angle of 76.7 (3)° with the plane of the cyclo-propane ring. In the crystal, inter-molecular N-H⋯O hydrogen bonds link the mol-ecules into chains running along the b axis.

Spectrofluorimetric determination of trace nitrite with a novel fluorescent probe.

A simple, sensitive and selective fluorimetric determination for trace nitrites was developed using an unsymmetrical rhodamine with a high fluorescence quantum yield and large Stokes shift. The method is based on the reaction of the unsymmetrical rhodamine with nitrite in an acidic medium to form a nitroso product, which has much lower fluorescence because the electron-withdrawing effect of the nitroso group influences the system of p-pi conjugation between N atom and benzene ring. Under optimum conditions, the fluorescence quenching intensity is linear over a nitrite concentration range of 1.0 x 10(-8) to 3.5 x 10(-7)M. The detection limit is 2.0 x 10(-10)M (S/N=3). The method was applied to the determination of nitrite in tap water and lake water with satisfactory results. The mechanism for the reaction is also reported.

(E)-2-(2-Chloro-3,3,3-trifluoro-prop-1-en-yl)-N-(2,4-dimethyl-phen-yl)-3,3-dimethyl-cyclo-propane-1-carboxamide.

The title compound, C(17)H(19)ClF(3)NO, crystallizes with three mol-ecules in the asymmetric unit. The aromatic ring makes dihedral angles of 38.69 (13), 46.68 (12) and 50.52 (11)° with the plane of the cyclo-propane ring in the three mol-ecules. The crystal packing is stabilized by inter-molecular N-H⋯O hydrogen bonds.

(E)-3-(2-Chloro-3,3,3-trifluoro-prop-1-en-yl)-2,2-dimethyl-N-p-tolyl-cyclo-propane-carboxamide.

There are two mol-ecules in the asymmetric unit of the title compound, C(16)H(17)ClF(3)NO. The benzene ring in each mol-ecule makes a dihedral angle of 66.6 (3)° [116.3 (4)° in the second mol-ecule] with the plane of the cyclo-propane ring. The F atoms of the CF(3) groups are disordered equally over two positions. The amide hydrogen is linked with the amide oxygen in another mol-ecule by an inter-molecular N-H⋯O hydrogen bond. The packing can be described as a dimeric arrangement of mol-ecules linked through N-H⋯O hydrogen bonds.

(E)-3-(2-Chloro-3,3,3-trifluoro-prop-1-en-yl)-2,2-dimethyl-N-(2-naphth-yl)cyclo-propane-carboxamide.

The title compound, C(19)H(17)ClF(3)NO, was synthesized from 3-[(E)-2-chloro-3,3,3-trifluoro-prop-1-en-yl]-2,2-dimethyl-cyclopropane-carboxylic acid and 2-aminona-phthalene. There are two molecules in the asymmetric unit. The dihedral angle between the naphthalene and cyclo-propane units is 111.6 (5)°. Molecules are connected into chains by intermol-ecular N-H⋯O hydrogen bonds. One of the Cl atoms is disordered over two positions with occupancies 0.653 (15) and 0.347 (15).

(E)-3-(2-Chloro-3,3,3-trifluoro-prop-1-en-yl)-N-(3-methoxy-phen-yl)-2,2-dimethyl-cyclo-propane-carboxamide.

The title compound, C(16)H(17)ClF(3)NO(2), was synthesized from 3-[(E)-2-chloro-3,3,3-trifluoro-prop-1-en-yl]-2,2-dimethyl-cyclo-propane-carboxylic acid and 3-methoxy-benzenamine. The propenyl and carboxamide substituents lie on the same side of the cyclo-propane ring plane, with the two methyl substituents on either side of the plane. The benzene ring makes a dihedral angle of 76.4 (3)° with the plane of the cyclo-propane ring. The crystal structure involves intermolecular N-H⋯O hydrogen bonds.

(E)-3-(2-Chloro-3,3,3-trifluoro-prop-1-en-yl)-2,2-dimethyl-N,N-diphenyl-cyclo-propane-carboxamide.

The title compound, C(21)H(19)ClF(3)NO, was synthesized from 3-[(E)-2-chloro-3,3,3-trifluoro-prop-1-en-yl]-2,2-dimethyl-cyclo-propane-carboxylic acid and diphenyl-amine. The propenyl and carboxamide substituents lie on the same side of the cyclo-propane ring plane, with the two methyl substituents on either side of the plane. The phenyl rings of the carboxamide are inclined at an angle of 84.6 (3)° to one another. The F atoms are disordered over two positions; the site occupancy factors are ca 0.6 and 0.4.

New fluorescent labels: 4- and 7-chlorofluorescein.

A new mixture of 4- and 7-chlorofluorescein were synthesized by condensation of resorcinol with 3-chlorophthalic anhydride in the presence of methanesulfonic acid or zinc chloride. These regioisomers were successfully separated by chromatography. The photophysical properties were examined and their absorption and emission maxima at long wavelength, high fluorescence quantum yield, and narrow emission bandwidth were found, highly favorable for detecting multiple target substances in the same sample. Furthermore, 4(7)-chlorofluorescein was found to be strongly pH-dependent between 4.0 and 8.0, and could be used as pH-sensitive fluorescent probe to measure intracellular pH.