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A series of novel 2D‐D‐π‐A‐type organic dyes, namely CCTTnA (n = 1–3), bearing bis(3,6‐di‐tert‐butylcarbazol‐9‐ylphenyl)aniline as an electron‐donor moiety (2D‐D), oligothiophene segments with a number of thiophene units from one to three units as π‐conjugated spacers (π), and cyanoacrylic acid as the electron acceptor (A) were synthesized and characterized as dye sensitizers for dye‐sensitized solar cells (DSSCs). These compounds exhibit high thermal and electrochemical stability. Detailed investigations of these dyes reveal that both peripheral carbazole donors (2D) have beneficial influence on the red‐shifted absorption spectrum of the dye in solution and dye adsorbed on TiO2 film, and the broadening of the incident monochromatic photon‐to‐current conversion efficiency (IPCE) spectra of the DSSCs, leading to enhanced energy conversion efficiency (η). Among these dyes, CCTT3A shows the best photovoltaic performance, and a maximal incident monochromatic photon‐to‐current conversion efficiency (IPCE) value of 80 %, a short‐circuit photocurrent density (Jsc) of 9.98 mA cm–2, open‐circuit voltage (Voc) of 0.70 V, and fill factor (FF) of 0.67, corresponding to an overall conversion efficiency η of 4.6 % were achieved. This work suggests that organic dyes based on this type of donor moiety or donor molecular architecture are promising candidates for improved performance DSSCs.

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Mangrove plants are the source of various secondary bioactive metabolites and have been used in traditional medicine for many diseases. This study aimed to investigate bioactive phytochemical components of two mangrove plants, Rhizophora mucronate and Rhizophora apiculata in the Rhizophoraceae family. Eight extracts of four parts (pod, leaf, twig, and bark) of each plant were prepared by maceration with a methanolic solvent. Phytochemical analysis was conducted through the aid of a standard test and was confirmed by quantitative analysis based on the determination of the total saponin, phenolic, and flavonoid contents. Free radical scavenging activity was studied in vitro by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) methods. Antibacterial activity was performed by the hole-plate diffusion method and determination of minimum inhibitory concentration (MIC) and minimum bactericidal concentration. The pod of R. mucronata predominantly showed the highest total saponin content [8.05 ± 0.50 mg escin equivalent (EE)/g CE], and the bark presented a great amount of phenolic and total flavonoid contents (2.12 ± 0.11 mg gallic acid equivalent/g CE and 6.73 ± 0.25 mg RU/g CE). R. mucronata showed greater free radical scavenging activity than Rhizophora apiculata at a concentration of 100 _g/ml supported by the DPPH and ABTS assays. Antibacterial screening showed that the maximum zone of inhibition was noted for R. mucronata extracts against Streptococcus agalactiae, Aeromonas hydrophila, Vibrio harveyi, and Vibrio parahemolyticus (8.50-13.56 nm). The R. mucronata pod extract had the lowest MIC to only A. hydrophila. Meanwhile, the R. mucronata bark extract had the lowest MIC to S. agalactiae and A. hydrophila. The higher antibacterial activity of R. mucronata extracts was consistent with the greater saponin, phenolic, and flavonoid contents and antioxidant activity of the extracts of these species with a significant value of p < 0.05. The present study highlighted that R. mucronata could be used as a potential source of bioactive compounds against aquatic pathogenic bacteria.

A new screening method for flunitrazepam in colourless alcoholic beverages based on a spectroscopic technique is proposed. Absorption and steady-state fluorescence of flunitrazepam and its protonated form with various acids were investigated. The redshift of the wavelength of maximum absorption was distinctively observed in protonated flunitrazepam. An emissive fluorescence at 472 nm was detected in colourless spirits (vodka and tequila) at room temperature. 2-M perchloric acid was the most appropriated proton source. By using electron ionization mass spectrometry and time-dependent density functional theory calculations, the possible structure of protonated flunitrazepam was identified to be 2-nitro-N-methylacridone, an acridone derivative as opposed to 2-methylamino-5-nitro-2'-fluorobenzophenone, a benzophenone derivative.