The first fluorescent sensor for medium-chain fatty acids in water: design, synthesis and sensing properties of an organic-inorganic hybrid material.

This paper reports the first fluorescent sensor for medium-chain fatty acids in water. The hybrid sensing material (S2) was prepared by the reaction of a rationally designed "recognition center", N-butyl-4-piperazin-1,8-naphthalimide, with a 3-glycidoxypropyl group which is pre-grafted on the interior of a mesoporous solid (MCM-41). The organo-functionalization of the mesoporous solid (MCM-41) was confirmed by FT-IR, 29Si MAS NMR and elemental analysis. The results of XRD, N2 physical adsorption-desorption, SEM and TEM studies proved that the organized structure of the nanoscopic porous solid is preserved after the reactions. The fatty acid-selective signaling behavior of S2 was investigated in water at pH = 5.80/7.16/8.00. This material displays much stronger fluorescence enhancement with C8-C12 fatty acids than with the shorter and longer chains in aqueous media, both in the absence and in the presence of aromatic acids.

Fluorescent ß-cyclodextrins modified by isomeric aminobenzamides: synthesis, conformational analysis, and fluorescent behaviors.

Three isomeric fluorescent ß-cyclodextrins bearing 2-, 3-, and 4-(2-aminoethyl)amino-N-butylbenzamide, respectively (1-3) have been synthesized. The conformations of these fluorescent CDs have been investigated by 2D NMR and induced circular dichromism. It is confirmed that the ortho isomer 1 takes a butyl-included conformation, while the other two isomers 2 and 3 display a phenyl-included conformation, respectively. The three fluorescent CDs 1-3 exhibited totally different self- and guest-inclusion fluorescence behavior. In the presence of adamantane carboxylate sodium (ADA) or deoxycholate sodium (DCA), the fluorescence intensity of 1 showed an enhancement over 1-fold, while 2 exhibited dramatic fluorescence quenching. Interestingly, the fluorescent responses of 3 toward two guests respectively were highly distinguishable. The fluorescence intensity of 3 only showed a slight increase upon the addition of ADA, but the addition of DCA led to a large decrease in fluorescence intensity. The investigations have been further carried out by 2D NMR, induced circular dichromism, fluorescence spectroscopy and molecular modeling to explore the relationships between the conformations and the fluorescence characteristics of CDs 1-3 in the absence and presence of guest molecules. On the basis of the above investigations, the origins for the different fluorescence behaviors have been proposed.

Displacement method to develop highly sensitive and selective dual chemosensor towards sulfide anion.

By utilizing a displacement method, a macrocyclic compound 1, could report the presence of sulfide anion, with the detection limit of 7.0 × 10(-7) mol/L; moreover, no interference was observed from other anions, including SO(3)(2-), HSO(3)(-), SO(4)(2-), ClO(4)(-), I(-), Br(-), Cl(-), F(-), IO(3)(-), HPO(4)(2-), PO(4)(3-), C(2)O(4)(2-), S(2)O(3)(2-), CO(3)(2-), AcO(-), CN(-) and P(2)O(7)(4-), making compound 1 a new, highly sensitive and selective sulfide anion chemosensor.

A ratiometric fluorescent chemodosimeter with selective recognition for sulfite in aqueous solution.

A fluorescent chemodosimeter containing a guanidiniocarbonylpyrrole and a 9-(aminomethyl)anthracene moiety has been synthesized. The sensor exhibits ratiometric fluorescence changes for SO(3)(2-) over other anions in 90% water/DMSO. The interesting ratiometric fluorescent changes for SO(3)(2-) are attributed to the fluorescence resonance energy transfer (FRET) and the SO(3)(2-) complex induced photochemical reaction.

Unexpected fluorescent behavior of a 4-amino-1,8-naphthalimide derived beta-cyclodextrin: conformation analysis and sensing properties.

A new fluorescent cyclodextrin shows unexpected and strong fluorescence enhancement upon binding of organic molecules, and the enhancing mechanism is found to be different from those reported in the literature.

Novel beta-cyclodextrin derivative functionalized polymethacrylate-based monolithic columns for enantioselective separation of ibuprofen and naproxen enantiomers in capillary electrochromatography.

A novel enantioselective polymethacrylate-based monolithic column for capillary electrochromatography was prepared by ring-opening reaction of epoxy groups from poly(glycidyl methacrylate-co-ethylene dimethacrylate) monolith with a novel beta-cyclodextrin derivative bearing 4-dimethylamino-1,8-naphthalimide functionalities. Conditions for the ring-opening reaction with respect to different reaction parameters were thoroughly optimized to obtain high electroosmotic flow, separation efficiency and enantioselectivity for the analytes. The nonaqueous mobile phase composition regarding acetonitrile-methanol ratio and the concentration of electrolyte were examined to manipulate the hydrophobic inclusion and anion-exchange interaction between the analytes and chiral stationary phase. It was observed that in addition to beta-cyclodextrin cavity, the electrostatic interaction exhibited pronounced influence on the enantioseparation of acidic analytes. Acidic enantiomers (ibuprofen and naproxen) could be separated with separation factor (alpha) values up to 1.08 and a maximum separation efficiency of 86000 plates/m could be achieved.

A highly selective fluorescent probe for pyrophosphate in aqueous solution.

A new 4-amino-1,8-naphthalimide-based fluorescent chemosensor bearing a guanidiniocarbonyl pyrrole moiety has been synthesized. The sensor displays a selective fluorescent enhancement with pyrophosphate over ATP, ADP, AMP and other inorganic anions in aqueous solution.

Macrocyclic polyamine-modified poly(glycidyl methacrylate-co-ethylene dimethacrylate) monolith for capillary electrochromatography.

1,4,10,13,16-Pentaazatricycloheneicosane-9,17-dione (macrocyclic polyamine)-modified polymer-based monolithic column for CEC was prepared by ring opening reaction of epoxide groups from poly(glycidyl methacrylate-co-ethylene dimethacrylate) (GMA-co-EDMA) monolith with macrocyclic polyamine. Conditions such as reaction time and concentration of macrocyclic polyamine for the modification reaction were optimized to generate substantial EOF and enough chromatographic interactions. Anodic EOF was observed in the pH range of 2.0-8.0 studied due to the protonation of macrcyclic polyamine at the surface of the monolith. Morphology of the monolithic column was examined by SEM and the incorporation of macrocyclic polyamine to the poly(GMA-co-EDMA) monolith was characterized by infrared (IR) spectra. Successful separation of inorganic anions, isomeric benzenediols, and benzoic acid derivatives on the monolithic column was achieved for CEC. In addition to hydrophobic interaction, hydrogen bonding and electrostatic interaction played a significant role in the separation process.

Nonlinear optical chromophores with pyrrole moieties as the conjugated bridge: enhanced NLO effects and interesting optical behavior.

A series of nonlinear optical (NLO) chromophores were successfully prepared, in which pyrrole moieties were the conjugated bridge. In comparison with their analogues containing furan or thiophene groups as the bridge, these chromophores demonstrated similar or enhanced NLO effects (up to 3.3 times) and interesting optical behavior. While the acceptor groups were malononitrile (Mal), 3-phenyl-5-isoxazolone (Iso), and 1,3-diethylthiobarbituric acid (Bar), the chromophores exhibited much blue-shifted maximum absorption wavelengths (lambda max) (up to 36 nm); however, the lambda max of the chromophore containing tricyanovinyldihydrofuran (TCF) as acceptor became much longer than that of the analogue (up to 75 nm).

An intramolecular charge transfer fluorescent probe: synthesis and selective fluorescent sensing of Ag+.

An intramolecular charge transfer (ICT) fluorescent probe, in which the thiourea derivative moiety is linked to the fluorescent 4-(dimethylamino) benzamide, has been designed and synthesized. The ions-selective signaling behaviors of the probe were investigated. Upon the addition of Ag+, an overall emission enhancement of 14-fold was observed. Compound 1 displayed highly selective chelation enhanced fluorescence (CHEF) effect with Ag+ over alkali, alkali earth metal ions and some transition metal ions in aqueous methanol solutions. The prominent selective and efficient fluorescent enhancing behavior could be utilized as a new chemosensing probe for the analysis of Ag+ ion in aqueous environment.

[Synthesis and spectral characterization of novel chiral macrocyclic dioxopolyamines].

Two novel chiral macrocyclic dioxopolyamines, which can be used as NMR chiral solvating agents (CSAs) for chiral carboxylic acids, were synthesized from L-proline through esterification, bridging and ring-closing reaction. With the aid of orthogonal experiments the optimum reaction conditions were determined: for (8S, 18S)-1, 4, 10, 13, 16-pentaaza-tricyclo [16.3. 0.04(4,8)] heneicosane-9,17-dione(2-a), reaction temperature 50 degrees C, reaction time 10 d, in nitrogen atmosphere, absolute MeOH, yield 34.9%, and m. p. 278-280 degrees C; for 13-phenyl-(8S, 18S)-1, 4, 10, 13,16-pentaaza-tricyclo [16.3. 0.0(4,8)] heneicosane-9,17-dione (2-b), reaction temperature at reflux, reaction time 20 d, in nitrogen atmosphere, absolute MeOH, yield 2.6%, and m. p. 243-245 degrees C. Their molecular structures were characterized by elemental analysis (EA), mass spectroscopy (MS), infrared spectroscopy (IR), and 1D and 2D nuclear magnetic resonance spectrometry (NMR). The main infrared absorption peaks and nuclear magnetic spectral bands of the compounds were assigned. The spectroscopic analytical result provides useful information for further study of the mechanism of host-guest interaction and for preparing new and effective CSAs.

DFT/TDDFT studies of the geometry, electronic structure and spectra of (12S)-1,4,7,10-tetraazadicyclo[10,3,0]-pentadecane-3,11-dione and its derivatives.

The FT-Raman and UV-visible spectra of (12S)-1,4,7,10-tetraazadicyclo[10,3,0]-pentadecane-3,11-dione and its derivatives were obtained and discussed. The harmonic vibrational wavenumbers and the corresponding Raman scattering activities in their electronic ground-states were calculated at the DFT-B3LYP/6-31G(d) level of theory. The calculated wavenumbers were then scaled and compared with the experimental values. The 7-(2,4-dinitrophenyl)-(12S)-1,4,7,10-tetrazadicyclo[10,3,0]-pentadecane-3,11-dione derivative has mainly an amide (II) character, while the others have an amide (I) character. Moreover, the different substituents do not cause a significant shift of the vibrational mode of the macrocyclic plane. The electronic vertical excitation energy and the oscillator strength were determined with the help of TDDFT calculations and by employing pure (BLYP) and hybrid (B3LYP, B3P86, and mPW1PW91) functionals together with the 6-31G(d) basis set. The BLYP functional reproduces the UV-vis absorption spectra better than the B3LYP, B3P86, or mPW1PW91 hybrid functionals. A dimolecular model, which considers hydrogen-bonded structures, proved that strong inter- and intramolecular hydrogen bonds are present in these compounds. Due to the transannular effect, the UV-vis absorption spectrum of macrocyclic dioxotetraamines is completely different from that of single amide compounds.