A series of anthracene-derived dyes for Cu2+-assisted CO sensing and bio-imaging: synthesis, performance, and mechanism

Endogenous CO acts as an important messenger for signal transduction and therapeutic effect in the human body. Fluorescent imaging appears to be a promising method for endogenous CO recognition, but traditional luminescent probes based on Pd-complexes suffered from defects of high cost. In this work, four anthracene-derived dyes having an = N-N = group were synthesized for Cu2+-assisted CO sensing. Their molecular structure, photophysical performance and spectral response to Cu2+ and CO were analyzed in detail. The optimal probe showed good selectivity and quenching effect to Cu2+, with PLQY (photoluminescence quantum yield) decreased from 0.33 to 0.04. The quenching mechanism was found as a static quenching mechanism by forming a non-fluorescent complex with Cu2+ (stoichiometric ratio = 1:1), as revealed by single crystal, EPR (electron paramagnetic resonance), and XPS (X-ray photoelectron spectroscopy) analysis. Such quenching effect could be reversed by CO, showing recovered fluorescence, with PLQY recovered to 0.32 within 328 s. Discussion on cellular endogenous CO imaging was included as well.

Series of Fluorescent Dyes Derived from Triphenylamine Structure for Cu2+ and In-Cell Carbon Monoxide Sensing: Synthesis and Performance

In this paper, triphenylamine served as the structural core and was bonded to aromatic groups having various substituents [-OH, -OMe, or -N(Et)2] by a =N-N= chain and then connected with aromatic groups having various substituents [-OH, -OMe, or -N(Et)2]. The geometric and electronic properties of these probes were examined. It was found that the presence of electron donors enhanced the selectivity and emission quantum yield (QY). When exposed to Cu2+, the fluorescence intensity decreased. The optimal probe (T5) showed a significant decrease in emission QY from 17.1 to 0.5% and recovered to 16.8% after exposure to CO for 342 s. The sensing mechanism was revealed to be static quenching, forming a nonfluorescent adduct between probe and Cu2+. After reacting with CO, Cu2+ was reduced to Cu+, and the probe emission was recovered. The bioimaging performance of the optimal probe was assessed as well.

Al3+ triggered aggregation induced emission of an anthracence based azine derivative in SDS medium

Single crystal X-ray structurally characterized anthracene appended unsymmetrical azine derivative, viz. 4-(anthracen-9-ylmethylene-hydrazonomethyl)-2-methoxy-phenol (L5) shows Al³⁺ assisted aggregation induced emission in SDS medium.

2-{(1E)-[(E)-2-(2,6-Di-chloro-benzyl-idene)hydrazin-1-yl-idene]meth-yl}phenol: crystal structure, Hirshfeld surface analysis and computational study

The title Schiff base compound, C14H10Cl2N2O, features an E configuration about each of the C=N imine bonds. Overall, the mol-ecule is approximately planar with the dihedral angle between the central C2N2 residue (r.m.s. deviation = 0.0371 Å) and the peripheral hy-droxy-benzene and chloro-benzene rings being 4.9 (3) and 7.5 (3)°, respectively. Nevertheless, a small twist is evident about the central N-N bond [the C-N-N-C torsion angle = -172.7 (2)°]. An intra-molecular hy-droxy-O-H⋯N(imine) hydrogen bond closes an S(6) loop. In the crystal, π-π stacking inter-actions between hy-droxy- and chloro-benzene rings [inter-centroid separation = 3.6939 (13) Å] lead to a helical supra-molecular chain propagating along the b-axis direction; the chains pack without directional inter-actions between them. The calculated Hirshfeld surfaces point to the importance of H⋯H and Cl⋯H/H⋯Cl contacts to the overall surface, each contributing approximately 29% of all contacts. However, of these only Cl⋯H contacts occur at separations less than the sum of the van der Waals radii. The aforementioned π-π stacking inter-actions contribute 12.0% to the overall surface contacts. The calculation of the inter-action energies in the crystal indicates significant contributions from the dispersion term.

Azines: synthesis, structure, electronic structure and their applications

Azines (2,3-diaza-1,3-butadienes): structure, electronic structure, tautomerism, and their applications in organic synthesis, medicinal chemistry and materials chemistry.

Application of rice (Oryza sativa L.) root endophytic diazotrophic Azotobacter sp. strain Avi2 (MCC 3432) can increase rice yield under green house and field condition

Use of plant-associated beneficial microbes, especially endophytes are getting popular day by day as they occupy a relatively privileged niche inside different plant tissues with lesser competition for food and shelter than rhizosphere. The effects of different physical factors like temperature, rainfall, and seasonal variation and UV radiation on plant growth promoting endophytic communities are less pronounced than those on the rhizospheric and phylloplane microbes. This present work has been compromised with further utilization of an indigenous rice (Oryza sativa L.) root endophytic Azotobacter sp. strain Avi2 (MCC 3432) (AzA) as a bio-formulation for sustainable rice production based on several physiological parameters (plant height, root length/weight, leaf area, yield, chlorophyll contain), in-vitro comparative plant growth promoting assays, greenhouse and field experiments (dry and wet season). Treatments with AzA exhibited higher yield as well as maximal chlorophyll fluorescence (Fm) of flag leaves in flowering and grain filling stages indicating higher photosynthetic rates. Scanning electron microscopic image of rice roots demonstrated accumulation of bacterial biofilm at the junction of primary and lateral root confirming the root-colonizing ability of the bacterium. The results of the study were quite encouraging as AzA exhibited better vegetative and reproductive growth of rice in pot and field experiment compared to formulated rhizospheric Azotobacter sp. (commercial product). Apart from that plants treated with AzA (supplemented 50% nitrogenous fertilizer of recommended dose) exhibited similar yield parameters when it was compared with the recommended dose of fertilizer (RDF; 120:60:60 mg N:P:K kg^-1 soil/ without any bacterial). Therefore, it can be concluded that application of this plant growth promoting endophyte can reduce a substantial amount of N-fertilizer for field application.

A multi-functional chemosensor for highly selective ratiometric fluorescent detection of silver(I) ion and dual turn-on fluorescent and colorimetric detection of sulfide

A multi-functional chemosensor 1 as silver and sulfide detector was synthesized by the combination of octopamine and 4-dimethylaminocinnamaldehyde. Sensor 1 exhibited a ratiometric fluorescence emission for Ag+ from blue to sky. The binding mode of 1 and Ag+ turned out to be a 1 : 1 ratio as determined using Job plot and electrospray ionization (ESI) mass spectral analyses. The sensing mechanism of 1 with silver ion was unravelled by 1H NMR titrations and theoretical calculations. Sensor 1 also discerned sulfide by enhancing fluorescence intensity and changing colour from yellow to colourless in aqueous solution. The sensing properties of 1 toward S2- were investigated by using ESI-mass analysis, Job plot and 1H NMR titrations. Moreover, 1 could be used as a detector for sulfide in a wide pH range.