Intramolecular charge transfer in 5-methoxy-2-(2-pyridyl)thiazole-derived fluorescent molecules with different acceptor or donor substituents.

On the basis of the rational derivation of 5-methoxy-2-(2-pyridyl)thiazole (2-MPT), we synthesized a new series of charge-transfer-based fluorescent molecules bearing different electronic donors or acceptors. The substituents range from strong electronic donors (e.g., amino and hydroxyl groups) to weak donating groups (e.g., proton and methyl groups) and electronic acceptors (e.g., pyridine ring). Through systematic investigation on the substituent-/polarity-dependent spectra (including room-temperature absorption, room-/low-temperature steady-state fluorescence spectra, and transient fluorescence lifetime characterization) and theoretical calculations, the emission properties of MPT derivatives are found to be governed by the rotation of the substituent around the triple bond axis, which produces distinct intramolecular charge transfer processes in either the twisted or planar excited states. The interconversion of excited-state geometry triggered by local interactions in polar solvents may produce a bathochromic shift of approximately 100 nm in fluorescence spectra. The solution state may also affect the ground- and excited-state conformation and hence results in the solvent-frozen-point sensitive fluorescence for some of the as-prepared molecules.

Diaqua-{6,6'-dimeth-oxy-2,2'-[ethane-1,2-diylbis(nitrilo-methyl-idyne)]diphenolato-κO,N,N',O'}manganese(III) perchlorate 18-crown-6 hemisolvate monohydrate.

In the cation of the title compound, [Mn(C(18)H(18)N(2)O(4))(H(2)O)(2)]ClO(4)·0.5C(12)H(24)O(6)·H(2)O, the Mn(III) ion is coordinated by two water O atoms, and two O atoms and two N atoms from the tetradentate 6,6'-dimeth-oxy-2,2'-[ethane-1,2-diylbis(nitrilo-methyl-idyne)]di-phenolate ligand, completing a distorted octa-hedral geometry. One O atom of the 18-crown-6-ether is disordered over two positions with occupancies of 0.70 (2) and 0.30 (2).

{6,6'-Dimeth-oxy-2,2'-[4-bromo-o-phenyl-enebis(nitrilo-methyl-idyne)]diphenolato}nickel(II) methanol solvate.

In the title compound, [Ni(C(22)H(17)BrN(2)O(4))]·CH(3)OH, the Ni(II) ion is in a slightly distorted square-planar geometry involving an N(2)O(2) atom set of the tetra-dentate Schiff base ligand. The asymmetric unit contains one nickel complex and one methanol solvent mol-ecule. The dihedral angle between the aromatic ring planes of the central aromatic ring and other two aromatic rings are 10.8 (3) and 6.0 (2)°. The crystal structure is stabilized by inter-molecular C-H⋯O and C-H⋯Br and by intra-molecular O-H⋯O hydrogen bonds.

(E)-2-[(2-Amino-4,5-dibromo-phen-yl)imino-meth-yl]-6-methoxy-phenol.

The title compound, C(14)H(12)Br(2)N(2)O(2), was prepared from the condensation of 4,5-dibromo-1,2-phenyl-enediamine and 2-hydr-oxy-3-methoxy-benzaldehyde in methanol. The N=C double bond shows a trans conformation and the dihedral angle between the aromatic ring planes is 5.9 (4)°. In the crystal structure, there are intra-molecular O-H⋯N and N-H⋯N and inter-molecular N-H⋯O hydrogen bonds, the latter resulting in inversion dimers.

Di-µ-chlorido-bis-[chlorido(N,N-di-methyl-ethylenediamine-κN,N')zinc(II)].

The centrosymmetric dinuclear title compound, [Zn(2)Cl(4)(C(4)H(12)N(2))(2)], is isostructural with its previously reported Cu(II) analogue [Phelps, Goodman & Hodgson (1976 ▶). Inorg. Chem.15, 2266-2270]. In the title compound, each of the Zn(II) ions is coordinated by two N atoms from a chelating N,N-dimethyl-ethylenediamine ligand, two bridging Cl atoms and one terminal Cl atom. The coordination environment is distorted square-pyramidal. The Zn-Cl bond distances of the two bridging Cl atoms are distinctly different: the equatorial Cl atom exbibits a Zn-Cl distance of 2.318 (1) Šand the axial Cl atom exbibits a Zn-Cl distance of 2.747 (2) Å, which is significantly longer. The mol-ecule can thus be seen as a dimer of two nearly square-planar monomeric units which are related to each other by an inversion center located in the middle of the dimer. Within one monomeric unit, the Zn atom, the two N atoms and the two Cl atoms are almost coplanar, with a mean deviation of only 0.05 (1) Šfrom the associated least-squares plane. The Zn⋯Zn distance within the dimer is 3.472 (3) Å. N-H⋯Cl and C-H⋯Cl hydrogen-bond inter-actions connect neighboring mol-ecules with each other.

Tris(1,10-phenanthroline-κN,N')iron(II) µ-oxido-bis[trichloridoferrate(III)] ethanol hemisolvate.

The title compound, [Fe(C(12)H(8)N(2))(3)][Fe(2)Cl(6)O]·0.5CH(3)CH(2)OH, consists of one [Fe(phen)(3)](2+) cation (phen = 1,10-phen-anthroline), one [Fe(2)Cl(6)O](2-) anion and one half-mol-ecule of ethanol. In the cation, the Fe(II) atom is coordinated by six N atoms from three phen ligands in a distorted octa-hedral geometry. In the bent anion, two Fe(III) atoms are connected by a bridging oxide O atom [bridging angle = 160.6 (4)°], and each Fe(III) atom is also coordinated by three Cl atoms, completing a distorted tetra-hedral geometry.

N-[4-(Prop-2-yn-yloxy)phen-yl]maleimide.

In the title compound, C(13)H(9)NO(3), the dihedral angle between the benzene and maleimide rings is 64.1 (2)°. In the crystal structure, mol-ecules interact via C-H⋯O inter-actions.

Note: Stability control of intermediate frequencies of a three laser far-infrared polarimeter-interferometer system.

Stability of the intermediate frequency (IF) in the far-infrared polarimeter-interferometer diagnostic system is critically important for the long pulse discharge experiments on the EAST tokamak. In this note, a real-time remote/local IF stability control system is described. The measured plasma parameters, including the Faraday rotation angle, electron density, lower hybrid wave, and plasma current, are obtained with the aid of this newly developed IF stability control system.

A novel sensitive turn-on fluorescent Zn2+ chemosensor based on an easy to prepare C3-symmetric Schiff-base derivative in 100% aqueous solution.

A C(3)-symmetric Schiff-base example of the new simple, low cost, highly water soluble, and sensitive turn-on fluorescent Zn(2+) chemosensor is described. The sensor was successfully applied to the detection of intracellular Zn(2+). Moreover, the sensor could also serve as a potential recyclable component in sensing materials. Notably, the color change is so obvious that all of the recycling process can be seen clearly by the naked eye.

A fluorescent-switch-based computing platform in defending information risk.

A molecular computing platform to defend against illegal information theft and invasion is obtained by the rational control of chemical reaction sequences in a newly prepared multiswitchable fluorophore 2-(4-aminophenylethylyl)-5-methoxy-2-(2-pyridyl)thiazole. Some of the fluorescent states with distinct recognition features are only activated through input-sequence-sensitive conversions. Chemically encoded user identity information can then be transmitted from a sequential logic unit to a combinational logic circuit, and hence, result in user-specific digital functionalities. The user's password entry is authorized prior to each computing step to check not only the user's identity, but also to reconfigure the molecular platform from the standby state to the corresponding operational state. Illegal accesses to the molecular computing platform are unable to activate the operation of the trusted users due to the incorrect activation processes, thereby ensuring the information is secured against information invasions.

A 1,8-naphthyridine-based fluorescent chemodosimeter for the rapid detection of Zn2+ and Cu2+.

A novel fluorescent chemodosimeter based on 1,8-naphthyridine exhibits high selectivity to Zn(2+) and Cu(2+). When 1-(7-acetamino-1,8-naphthyridyl)-2-(6-diacetaminopyridyl)ethene was mixed with CuCl2, hydrolysis of the acetamino group catalyzed by Cu(2+) complex was first observed. Resulting from coordination and hydrolysis catalyzed by the corresponding complex of Zn(2+) or Cu(2+), the highly effective fluorescent detection of Zn(2+) and Cu(2+) is realized with Zn(2+)-selective dual-emission and Cu(2+)-selective ON-OFF behavior.