We designed and synthesized a new colorimetric chemosensor L based on the combination of 3-hydroxy-1, 4-dioxo-1, 4dihydronaphthalene-2-carbaldehyde 2 and diaminomaleonitrile 3 moiety. The recognition abilities of the probe with a range of metal ions were evaluated and their optical properties have been systematically investigated. The chemosensor L exhibited well defined naked -eye visible color changes from yellow to pink for Hg 2+ in acetonitrile. Other ions, including Na + , Ca 2+ , CO 2+ , Ni 2+ , Cu 2+ , Mn 2+ , Sn 2+ , Hg 2+ , Fe 3+ , and Th 4+ had a negligible influence on the probe behaviour. The limit of detection (LOD) were 1.1x10 -7 M using the UV-vis changes. The selective recognition of Hg 2+ ions, it forms a 1:1 stoichiometric complex involving naphthoquinone hydroxyl and diaminomaleonitrile nitrogen functionality. The complex formations were proposed to be in 1:1 ratio based on Job plot, 1 H NMR titrations, ESI -mass spectrometry analysis and DFT calculations. Test strips based on L were fabricated, which could act as a convenient and efficient Hg 2+ test kits. The results consistently indicated that the Lawsone -DAMN was the ideal sensor, which can be utilised to monitor Hg 2+ in solution over a wide pH range.
Graphical AbstractA highly sensitive and selective chemosensor L exhibited well defined naked -eye visible color changes from yellow to pink for Hg 2+ in acetonitrile. The selective recognition of Hg 2+ ions, it forms a 1:1 stoichiometric complex involving naphthoquinone hydroxyl and diaminomaleonitrile nitrogen functionality.
The azo and styryl disperse dyes were synthesized by using 2-hydroxy-1,4-naphthoquinone (Lawsone) 1 and different substituted aromatic anilines and/or aldehydes. The structures of the dyes were confirmed using FT-IR, 1 H-NMR, MS, and HRMS spectral analysis. The dyes displayed a broad absorption maximum in the visible region between 426 and 490 nm. The present paper deals with the application of azo and styryl disperse dyes on polyester and nylon fiber, color characteristics, and fastness properties. The color strength (K/S value) has been found to be very good in all dyed polyester samples. The color fastness with respect to light exposure, washing, and rubbing was quite satisfactory for all dyed polyester compared to the nylon samples.
5-Hydroxybenzo[a]phenazine-6-carbaldehyde was synthesized and condensed with substituted active methylene compounds to obtain four novel phenazine fused coumarin dyes. Solutions of imidazole containing dyes in various solvents exhibited yellow to orange fluorescence while benzothiazole containing dyes showed brilliant bluish green fluorescence. The dyes showed pronounced negative solvatochromism. However, the emission experienced progressive red shift with increasing polarity. The excited states of these dyes are proved to be more polar than the ground state. The dyes showed fairly good quantum yield in the range 0.1-0.7, and displayed high thermal stability, as determined using thermo gravimetric analysis. The density functional theory computations showed that intramolecular charge transfer occurs from the 3 position to the 7 position. The excited state computation using time dependent functional theory predicted the emission well.
The novel benzofused phenazine π-conjugated skeleton with a coumarin and isophoron core was synthesized, characterized, and condensed with suitably substituted active methylene compounds by classical Knoevenagel condensation reaction to obtain novel mono-styryl dyes 6a-6d. These novel styryl dyes have hue varying from yellow to violet. The geometries of the styryl dyes were optimized at B3LYP/6-31G (d) level of theory, and their electronic excitation properties were evaluated using density functional theory.
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