: 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

Data Reduction And Error Analysis For The Physical Sciences

Triggered by the resounding success of cisplatin, the past decades have seen tremendous efforts to produce clinically beneficial analogues. The recent achievement of oxaliplatin for the treatment of colon cancer should, however, not belie the imbalance between a plethora of investigated complexes and a very small number of clinically approved platinum drugs. Strategies opening up new avenues are increasingly being sought using complexes of metals other than platinum such as ruthenium or gallium. Based on the chemical differences between these metals, the spectrum of molecular mechanisms of action and potential indications can be broadened substantially. Other approaches focus on complexes with tumour-targeting properties, thereby maximizing the impact on cancer cells and minimizing the problem of adverse side effects, and complexes with biologically active ligands.

Antitumour metal compounds: more than theme and variations

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.

2004아테네 올림픽대회출전 한국레슬링 대표선수의 무산소성 운동능력 및 등속성 근력

Novel photoluminescent hemi-disclike liquid crystalline Zn(II) complexes of [N2O2] donor 4-alkoxy substituted salicyldimine Schiff base with aromatic spacer

A new series of nondisc-like ZnII Schiff base complexes of the type [Zn (4-CnH2n+1O)2 salophen], n = 14, 16, 18, salophen = N,N′-phenylenebis(salicylideneiminato), have been prepared and their mesogenic, photophysical properties investigated. The mesomorphic behaviour of these compounds was studied by differential scanning calorimetry, polarized optical microscopy and X-ray diffraction (XRD) techniques. The ligands are found to be nonmesogenic, but their complexes exhibited a columnar mesomorphism. The XRD-study revealed that the molecules are self-organized into columnar mesophase of the primitive rectangular (Colr) and/or monoclinic oblique type. At room temperature with 360 nm excitation, all the complexes showed green emission in dichloromethane solution (ca. 507 nm, Φ = 22 %) as well as in the solid state (ca. 516 nm, Φ = 9 %). The DFT calculations were performed using the DMol3 program at BLYP/DNP level to obtain the stable electronic structure of the complex.

Novel Green Light Emitting Nondiscoid Liquid Crystalline Zinc(II) Schiff-Base Complexes

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+

Synthesis, reactivity, thermal, electrochemical and magnetic studies on iron(III) complexes of tetradentate Schiff base ligands

A new coumarin based Schiff-base chemosensor, (E)-7-(((8-hydroxyquinoline-2-yl)methylene)amino)-4-(trifluoromethyl)-2H-chromen-2-one (H12L) was designed and synthesized. This chemosensor was evaluated as a colorimetric sensor for Fe3+ and fluorescence “turn on–off” response to Zn2+ and Cu2+ using steady-state absorption and fluorescence spectroscopy. In the presence of Fe3+ and Zn2+, the absorption intensity as well as the fluorescence emission intensity increases drastically compared to other surveyed metal ions, with a distinct color change which provides naked eye detection. However, in the presence of Cu2+, it also exhibits quenching of fluorescence emission intensity which may be due to the paramagnetic nature of Cu2+ ions. The stoichiometric ratio and binding constant were calculated using the Benesi–Hildebrand relation and Job's plot analyses, giving 1 : 1 stoichiometry. The interaction and binding nature of H12L with Zn2+ ions was further confirmed by 1H NMR titration assay and ESI-mass spectral analysis. The reversibility of H12L was also studied using EDTA as a chelating ligand. Moreover, H12L exhibits two INHIBIT logic gates with two different chemical inputs (i) Zn2+ (IN1) and Cu2+ (IN2) and (ii) Zn2+ (IN1) and EDTA (IN2) and the emission as output. Again, an IMPLICATION logic gate is obtained with Cu2+ and EDTA as chemical inputs and emission as the output mode. Both H12L and metal-complexes were optimized using density functional theory and vibrational frequency calculations confirm that both are at local minima on the potential energy surfaces. The corresponding energy difference between the HOMOs and LUMOs of H12L, Zn-complex and Cu-complex are found to be 2.11, 0.81 and 0.17 eV, respectively.

Paritosh Mondal

Papers

Novel photoluminescent hemi-disclike liquid crystalline Zn(II) complexes of [N2O2] donor 4-alkoxy substituted salicyldimine Schiff base with aromatic spacer

Novel Green Light Emitting Nondiscoid Liquid Crystalline Zinc(II) Schiff-Base Complexes

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

Synthesis, reactivity, thermal, electrochemical and magnetic studies on iron(III) complexes of tetradentate Schiff base ligands

A highly efficient and selective coumarin based fluorescent probe for colorimetric detection of Fe3+ and fluorescence dual sensing of Zn2+ and Cu2+