: The unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio. Harmonic force fields are obtained using Density Functional Theory (DFT), MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set. DFT calculations use the Local Spin Density Approximation (LSDA), BLYP, and Becke3LYP (B3LYP) density functionals. Mid-IR spectra predicted using LSDA, BLYP, and B3LYP force fields are of significantly different quality, the B3LYP force field yielding spectra in clearly superior, and overall excellent, agreement with experiment. The MP2 force field yields spectra in slightly worse agreement with experiment than the B3LYP force field. The SCF force field yields spectra in poor agreement with experiment.The basis set dependence of B3LYP force fields is also explored: the 6-31G* and TZ2P basis sets give very similar results while the 3-21G basis set yields spectra in substantially worse agreements with experiment. jg

Ab initio calculation of vibrational absorption and circular dichroism spectra using density functional force fields

Fluorescent probes for hydrogen sulfide detection and bioimaging

Considerable amount of research has been carried out on designing and improving metal-recognition methodologies in environmental and biological media. The development of fluorescent-based techniques has proven to be an important milestone for non-invasive metal detection and quantification in a multichannel environment. Metals as natural components of the Earth's crust are generally present in trace concentrations in environmental samples, wherein humic substances have a complexation affinity toward them. Iron, zinc and copper are the 1st, 2nd and 3rd most abundant elements that are indispensable to the human body in trace amounts as they play crucial roles in many biological processes. However, unregulated amounts either an excess or deficiency may exacerbate deterioration of the vital organs and trigger the progression of complications. In addition to these three essential elements, mercury is widely considered to be one of the most hazardous pollutants and highly dangerous elements due to its recognized accumulative and toxic effects in the environment and in biological media. In the present study, we attempted to summarize all the recently developed fluorescent signaling materials for the detection of Cu2+, Fe2+/Fe3+, Zn2+ and Hg2+. The spectral shifts in the molecules on metal chelation, the mode of complexation and the stoichiometries of the resulting adducts have been discussed in detail. Furthermore, we highlight molecules that have been reported as an intracellular metal detector via bioimaging, which can be useful for the future design and development of cell-viable and membrane-permeable molecular probes.

Optical sensor: a promising strategy for environmental and biomedical monitoring of ionic species

Herein, a new fluorescence turn-on chemosensor 2-(4-(1,2,2-triphenylvinyl)phenoxy)acetic acid (TPE-COOH) specific for Al3+ was presented by combining the aggregation-induced-emission (AIE) effect of tertaphenylethylene and the complexation capability of carboxyl. The introduction of carboxylic group provides the probe with good water-solubility which is important for analyzing biological samples. The recognition toward Al3+ induced the molecular aggregation and activated the blue fluorescence of the TPE core. The high selectivity of the probe was demonstrated by discriminating Al3+ over a variety of metal ions in a complex mixture. A detection limit down to 21.6 nM was determined for Al3+ quantitation. Furthermore, benefiting from its good water solubility and biocompatibility, imaging detection and real-time monitoring of Al3+ in living HeLa cells were successfully achieved. The AIE effect of the probe enables high signal-to-noise ratio for bioimaging even without multiple washing steps. These superiorit...

Fluorescence Turn-On Chemosensor for Highly Selective and Sensitive Detection and Bioimaging of Al3+ in Living Cells Based on Ion-Induced Aggregation

A crystalline coordination polymer (CP) photocatalyst (Cu-RSH) which combines redox-active copper centers with photoactive rhodamine-derived ligands remains stable in acid and basic solutions from pH 2 to 14, and efficiently catalyzes dihydrogen evolution at a maximum rate of 7.88 mmol g−1 h−1 in the absence of a mediator and a co-catalyst. Cyclic voltammetry, control experiments, and DFT calculations established that copper nodes with open coordination sites and favorable redox potentials, aided by spatially ordered stacking of rhodamine-based linkers, account for the high catalytic performance of Cu-RSH. Emission quenching, time-resolved fluorescence decay, and transient photocurrent experiments disclosed the charge separation and transfer process in the catalytic system. The present study demonstrates the potential of crystalline copper CPs for the practical utilization of light.

A Crystalline Copper(II) Coordination Polymer for the Efficient Visible‐Light‐Driven Generation of Hydrogen

An On–Off–On type fluorescent sensor (HL) has been developed, which exhibited high selectivity and sensitivity for Cu2+ over other common ions in 100% aqueous solution. Once HL combined with Cu2+, blue fluorescence was almost completely quenched and the L-Cu ensemble was formed. Moreover, the ensemble showed high specificity for S2− based on the displacement approach, and no interferences were observed in the presence of other anions. Such fluorescence modulation behavior simulates the performance of an IMPLICATION logic gate. In addition, the fluorescent sensor was successfully applied to fluorescent cellular imaging implying potential applications in physiological and environmental systems.

New fluorescent sensor for Cu2+ and S2− in 100% aqueous solution based on displacement approach

A water-soluble rhodamine-based derivative (L) has been rationally designed for selective recognition of Al(3+) in aqueous medium with good sensitivity. The addition of Al(3+) to the aqueous solution of L induces a remarkable fluorescence enhancement along with obvious color change detected by the naked eye, due to the ring-opening mechanism of the rhodamine spirolactam, which has been proved by single crystal diffraction analyses directly. The recognizing behavior has been investigated both experimentally and computationally. Furthermore, the fluorescent probe can also be used as a bioimaging reagent for detection of Al(3+) in living cells.

A new fluorescent probe for Al3+ based on rhodamine 6G and its application to bioimaging

A new fluorescence sensor ( L ) derived from 8-hydroxy-2-methylquinoline has been developed. This sensor can selectively detect Cd 2+ in aqueous buffer solution based on chelation enhanced fluorescence (CHEF) and exhibit an almost 30-fold fluorescence increase. Besides, the complex ( LCd ) can also be considered as a good ON–OFF sensor for Hg 2+ based on photoinduced electron transfer (PET). The sensor could be applied for fluorescence microscopic imaging.

A new highly selective fluorescent sensor for detection of Cd2+ and Hg2+ based on two different approaches in aqueous solution

A novel fluorescent probe (L) based on acridine was rationally designed and synthesized. The fluorescent probe exhibited good selectivity and sensitivity toward Cr3+ in methanol. Meanwhile, the L-Cr3+ solution also displayed excellent selectivity to PO43− by a displacement approach. Moreover, the probe L could be used in neutral methanol aqueous medium, which had potential applications in biological and environmental systems. More importantly, both L and the L-Cr3+ complex had cell permeability and were successfully demonstrated in living MGC-803 cells for the detection of Cr3+ and PO43−, respectively.

A novel acridine-based fluorescent probe for the cascade recognition of Cr3+ and PO43−

The invention belongs to the technical field of metal ion detection and in particular relates to a rhodamine 6G-based Cu fluorescence probe molecule as well as a preparation method and an application thereof. The fluorescence probe molecule which takes rhodamine hydrazide as a matrix and has a form of modifying Schiff base by using 3-formyl methylsalicylate has a structure as follows: the probe molecule has no florescence in an N,N-2-methylformanamide solution; the fluorescence intensity is rapidly enhanced and can reach an effect of identification by naked eyes along with the visible color change after Cu is added; and after sulfur anions are added, sulfur ions are combined with copper ions, coordinate copper ions are released, the rhodamine hydrazide returns to a closed-loop state again, the fluorescence intensity of the system is rapidly reduced, and therefore the reversible operation of the fluorescence probe molecule is achieved. The probe molecule exerts the characteristic of strong anti-jamming capability in the system with coexistence of copper ions and other multiple metal ions and is high in sensitivity and sensitivity and can be well applied to copper ion detection in environment pollution.

Yan Fu

Papers

New fluorescent sensor for Cu2+ and S2− in 100% aqueous solution based on displacement approach

A new fluorescent probe for Al3+ based on rhodamine 6G and its application to bioimaging

A new highly selective fluorescent sensor for detection of Cd2+ and Hg2+ based on two different approaches in aqueous solution

A novel acridine-based fluorescent probe for the cascade recognition of Cr3+ and PO43−

Rhodamine 6G-based Cu fluorescence probe molecule and preparation method thereof