1,721,119 research outputs found
Application of New Boradiaza-s-indacene Derivatives in Anion sensing and Molecular Logic Gates
No full textThree-point recognition and selective fluorescence sensing of L-DOPA
No full textA phenylboronic acid derivative of a well-known dye (Lucifer yellow) recognizes L-DOPA through a combination of reversible esterification, charge transfer, and electrostatic interactions. The selective recognition event is signaled by a drop in the emission intensity of the fluorescent chemosensor
Signal ratio amplification via modulation of resonance energy transfer: Proof of principle in an emission ratiometric Hg(II) sensor
No full textBoradiazaindacene dyads designed as energy transfer casettes can be modified to signal cation concentrations ratiometrically. If the energy transfer efficiency is increased via changing spectral overlap on cation binding, an enhancement of emission signal ratios can be obtained. A larger range of ratios results in highly improved sensitivity to analyte concentrations. We demonstrate this approach in a de novo design of a novel and highly selective ratiometric chemosensor for Hg(II) ions
Ion sensing coupled to resonance energy transfer: A highly selective and sensitive ratiometric fluorescent chemosensor for Ag(I) by a modular approach
No full textWe report a novel dimeric boradiazaindacene dye which can be converted in one step to an efficient resonance energy transfer (RET) dyad. In addition, if this modification is done with appropriate ligands, RET can be coupled to ion sensing. The utility of this approach is demonstrated in a highly selective, emission ratiometric chemosensor for Ag(I)
Thinking Outside the Cage: Controlling the Extrinsic Porosity and Gas Uptake Properties of Shape-Persistent Molecular Cages in Nanoporous Polymers
No full textWe present a new strategy to introduce local-order into amorphous nanoporous polymers using shape-persistent organic cage compounds as molecular building blocks in the synthesis of porous cage frameworks (pCAGEs) without any metal catalyst under environmentally benign conditions. We have demonstrated that by varying the size and dimension of the organic linkers extrinsic porosity of organic cages within nanoporous polymers can be controlled, thus allowing us to tune the surface area and gas uptake properties of amorphous pCAGEs. pCAGEs (SA(BET) = 628.7-844.3 m(2) g(-1)) revealed significantly high CO, uptake capacities (up to 4.21 mmol g(-1) at 1 bar, 273 K) with prominent CO2/N-2 IAST selectivities (up to 100). Unlike previously reported triazine-based polymers, pCAGEs showed exceptional isosteric heats of adsorption (Q(st)) values up to 42.9 kJ mol(-1) for CO2 at high loading. We attribute the high affinity of CAGE toward CO2 to the presence of a "cage effect" arising from ultramicroporosity (intrinsic porosity) of CAGE monomers. To prove the cage effect, we have synthesized a control polymer incorporating half-CAGEs as monomeric units. The resulting polymer showed substantially lower Q(st) values compared to the CAGE and pCAGEs indicating the presence of the cage effect. In addition, the control over the surface area in the case of control polymer was lost completely, thus showing the importance of CAGE monomers as building blocks and the resulting local-order
Difluorobora-s-diazaindacene dyes as highly selective dosimetric reagents for fluoride anions
No full textDifltiorobora-s-diazaindacene derivatives are shown to report fluoride ions selectively in acetone solutions; both absorption and emission characteristics are drastically altered, and as a result, (his hitherto unknown reaction transforms the BODIPY(R) class of dyes into highly selective chromogenic and dual channel fluorogenic reagents for fluoride
A sensitive fluorescent chemosensor for anions based on a styryl-boradiazaindacene framework
No full textLong wavelength emitting, extended conjugation boradiazaindacenes are novel dyes with considerable ICT character. By appending a dipicolylaminylethylamine group, the parent compound was transformed into a fluorescent dye with a strong chelating ability for Zn(II) ions. The zinc complex which has bright orange fluorescence, reversibly signals anions with very large changes in both the absorption and the emission spectra. The remarkable change in the emission intensity is explained in relation to the electron donating capacity of the substituent on the styryl functionality
Graphene/ZIF-8 composites with tunable hierarchical porosity and electrical conductivity
No full textThe development of hierarchical metal-organic frameworks (MOFs) incorporating interconnected micro- and mesopores has been of considerable interest in gas separation, energy storage and catalysis due to the efficient mass transfer kinetics through mesopores. Here, we report the preparation of graphene/ZIF-8 nanocomposites with tunable hierarchical porosity and surface areas, wherein the distribution of micro- and mesopores along with the particle size of ZIF-8 crystals was controlled by simply varying the annealing temperature of graphene oxide sheets. These nanocomposites showed superior CO2 uptake capacities up to 17 mmol g(-1) at 303 K, 35 bar to ZIF-8 due to the synergistic effect of the graphitic surface and ZIF-8 crystals, thus offering a new direction to further improve the gas uptake capacity of MOFs, while simultaneously achieving fast mass transfer of gas molecules into the adsorbent through mesopores. Furthermore, the presence of graphitic templates (20 wt%) introduced electrical conductivity up to 64 S m(-1) into an insulating MOF such as ZIF-8. Importantly, we still observed an electrical conductivity of 2 S m(-1) with graphene loadings as low as 2.5 wt%. This present approach not only provides a new direction for the effective and facile synthesis of hierarchical porous materials but also paves the way for the introduction of electrical/thermal conductivity into insulating MOF structures
Effective PET and ICT switching of boradiazaindacene emission: A unimolecular, emission-mode, molecular half-subtractor with reconfigurable logic gates
No full textWe report a unimolecular system functioning as a combinatorial logic circuit for half-subtractor. The emission characteristics can be modulated by chemical inputs, and when followed at two different wavelengths, two functionally integrated logic gates XOR and INHIBIT are obtained. Both logic gates function in the emission mode, and with very large differences in the signal intensity allowing unequivocal assignment of logic-0 and logic-1
Cation modulation of carbonyldipyrrinone (CDP) fluorescence: emission-ratiometric sensing of calcium
No full textOptically dilute solutions of 2,3,7,8-tetraethyl-N,N'-carbonyldipyrrinone displays an absorbance peak at 401 nm and an emission peak at 493 nm in acetonitrile. The two carbonyl groups in the structure seems to be optimally placed for cation coordination, and when calcium ions are added in the form of a perchlorate salt, a remarkable bathochromic change in the absorption and emission spectrum takes place: the absorption peak shifts by 24 nm and the emission peak shifts by 49 nm towards the red end of the visible spectrum. The shift in the emission spectrum allows wavelength ratiometric assessment of calcium concentration. In addition, the response is highly selective with respect to the cations added
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