Data Reduction And Error Analysis For The Physical Sciences

Boron dipyrromethene (BODIPY) derivatives 1 and 2 consisting of donor and acceptor units with dual photoresponses to solvent polarity and luminogen aggregation are developed through taking advantage of twisted intramolecular charge transfer (TICT) and aggregation-induced emission (AIE) processes. In nonpolar solvents, the locally excited (LE) states of the BODIPY luminogens emit intense green lights. Increasing solvent polarity brings the luminogens from the LE state to the TICT state, causing a large bathochromic shift in the emission color but a dramatic decrease in the emission efficiency. The red emission is greatly boosted by aggregate formation or AIE effect: addition of large amounts of water into the solutions of 1 and 2 in the polar solvents causes the luminogens to aggregate supramolecularly and to emit efficiently. The emission can be enhanced by increasing solvent viscosity and decreasing solution temperature, indicating that the AIE effect is caused by the restriction of the intramolecular ro...

Twisted Intramolecular Charge Transfer and Aggregation-Induced Emission of BODIPY Derivatives

Coumarins are a very large family of compounds containing the unique 2H-chromen-2-one motif, as it is known according to IUPAC nomenclature. Coumarin derivatives are widely found in nature, especially in plants and are constituents of several essential oils. Up to now, thousands of coumarin derivatives have been isolated from nature or produced by chemists. More recently, the coumarin platform has been widely adopted in the design of small-molecule fluorescent chemosensors because of its excellent biocompatibility, strong and stable fluorescence emission, and good structural flexibility. This scaffold has found wide applications in the development of fluorescent chemosensors in the fields of molecular recognition, molecular imaging, bioorganic chemistry, analytical chemistry, materials chemistry, as well as in the biology and medical science communities. This review focuses on the important progress of coumarin-based small-molecule fluorescent chemosensors during the period of 2012-2018. This comprehensive and critical review may facilitate the development of more powerful fluorescent chemosensors for broad and exciting applications in the future.

Coumarin-Based Small-Molecule Fluorescent Chemosensors.

Colorimetric metal ion sensors – A comprehensive review of the years 2011–2016

Schiff bases and their metal complexes have become well-known for catalytic (e.g., in various synthetic processes) and biological properties (e.g., antifungal, antibacterial, anti-malarial, and antiviral characteristics) since their discovery by Hugo Schiff in 1864. As synthetic compounds, they are employed as versatile tools in numerous applications such as fluorescent turn-on/turn-off sensors for the determination of diverse analytes (e.g., metallic components). As such, they can offer a way to identify toxic ions and/or to provide their speciation in environmental media. This review covers a broad range of Schiff bases that are used in sensing applications for metallic cations and anions in various kinds of environmental and biological media.

A review of the applications of Schiff bases as optical chemical sensors

Interaction of cinnamic acid derivatives with serum albumins: A fluorescence spectroscopic study

Fluorescent chemosensor based on sensitive Schiff base for selective detection of Zn2

Fluorescence behavior of intramolecular charge transfer state in trans-ethyl p-(dimethylamino)cinamate

A new coumarin based Schiff-base dual chemosensor-( E )-2-(((8-hydroxyquinolin-2-yl)methylene)amino)-6H-benzo[c]chromen-one (H 10 L) was synthesized and characterized. This chemosensor was evaluated as a colorimetric sensor for Fe 3+ and fluorescence turn-on response for Zn 2+ among the various survey metal ions. The stoichiometric ratio and association constant were evaluated using Benesi-Hildebrand relation giving 1:1 stoichiometry. This further corroborated 1:1 complex formation based on Job’s plot analyses. The complex solution of H 10 L with Zn 2+ ion exhibited reversibility with EDTA and regenerate free ligand for further Zn 2+ sensing. H 10 L exhibits two INHIBIT logic gates with two different chemical inputs (i) Zn 2+ (IN1) and Cu 2+ (IN2) and (ii) Zn 2+ (IN1) and EDTA (IN2) and the emission as an output. Again, an IMPLICATION logic gate is obtained with Cu 2+ and EDTA as chemical inputs and emission as output mode. Both free ligand as well as metal-complexes was optimised using density functional theory. The calculated vibrational frequency confirms that both are at local minima on the potential energy surfaces. The corresponding energy difference between HOMO and LUMO of H 10 L, Zn-complex and Cu-complex are found to be 3.67, 1.63 and 2.01 eV, respectively. The Cu-complex is found to be more stable than Zn-complex as Cu-complex has higher hardness value compare to Zn-complex.

A new coumarin based dual functional chemosensor for colorimetric detection of Fe3+ and fluorescence turn-on response of Zn2+

Intramolecular charge transfer (ICT) behavior of trans -ethyl p -(dimethylamino)cinamate (EDAC) in various solvents has been studied by steady-state absorption and emission, picosecond time-resolved fluorescence spectroscopy and femtosecond transient absorption experiments as well as time-dependent density functional theory (TDDFT). Large fluorescence spectral shift in more polar solvents indicates an efficient charge transfer from the donor site to the acceptor moiety in the excited state compared to the ground state. The energy for 0,0 transition ( ν 0,0 ) for EDAC shows very good linear correlation with static solvent dielectric property. The relaxation dynamics of EDAC in the excited state can be effectively described by a “three state” model where, the locally excited (LE) state converts into the ICT state within 350 ± 100 fs. A combination of solvent reorganization and intramolecular vibrational relaxation within 0.5–6 ps populates the relaxed ICT state which undergoes fluorescence decay within few tens to hundreds of picoseconds.

T. Sanjoy Singh

Papers

Interaction of cinnamic acid derivatives with serum albumins: A fluorescence spectroscopic study

Fluorescent chemosensor based on sensitive Schiff base for selective detection of Zn2

Fluorescence behavior of intramolecular charge transfer state in trans-ethyl p-(dimethylamino)cinamate

A new coumarin based dual functional chemosensor for colorimetric detection of Fe3+ and fluorescence turn-on response of Zn2+

A combined experimental and theoretical study on photoinduced intramolecular charge transfer in trans-ethyl p-(dimethylamino)cinamate