Symmetrical Azine Colorimetric and Fluoromteric Turn-Off Chemosensor for Formaldehyde Detection

Abstract

Azine derivative 6,6'-((1E,1'E)-hydrazine-1,2-diylidenebis(methanyly-lidene))bis (3,4-dimethoxy-aniline) CHA has been synthesized by condensation of 6-nitroveratraldehyde with malononitrile followed by reduction using 10% Pd/C and hydrazine hydrate. In the presence of formaldehyde, CHA chemosensor in ethanol showed a yellow-to-red color change observable by the naked eyes and 'turn off' type fluorescence quenching in ethanol. This phenomenon was confirmed by UV-Vis, fluorescence and 1 H NMR spectroscopy. The CHA spectra in ethanol was shifted from 412 to 509 nm after addition of formaldehyde. Fluorescence intensity of CHA gradually decreased with the increase of formaldehyde concentrations. Furthermore, paper strips loaded-CHA were fabricated and served to detect formaldehyde qualitatively. The detection limit of the CHA probe to formaldehyde is 0.2 M. ABSTRAKTerbitan azina CHA 6,6'-((1E,1'E)-hidrazina-1,2-diilidenebis(metanili-liden))bis (3,4-dimetoksi-anilin) telah disintesis dengan pemeluwapan 6-nitroveratraldehid dengan malononitril diikuti dengan pengurangan menggunakan 10% Pd/C dan hidrat hidrazina. Dengan kehadiran formaldehid, kemoderia CHA dalam etanol menunjukkan perubahan warna daripada kuning kepada merah yang boleh diperhatikan oleh mata kasar dan 'mematikan' jenis pemelindapan kependarfluoran dalam etanol. Fenomena ini disahkan oleh UV-vis, kependarfluoran dan spektroskopi 1 H NMR. Spektrum CHA dalam etanol telah beralih daripada 412 kepada 509 nm selepas penambahan formaldehid. Keamatan kependarfluoran CHA secara beransur-ansur menurun dengan peningkatan kepekatan formaldehid. Tambahan pula, jalur kertas yang dimuatkan-CHA telah direka dan digunakan untuk mengesan formaldehid secara kualitatif. Had pengesanan prob CHA kepada formaldehid adalah 0.2 M.

Recent Progress in the Development of Organic Chemosensors for Formaldehyde Detection

“…39 The former probe has a lower LOD with 30 μM (0.03 M) than the CHA probe (0.20 M). 40 Wei et al took HCy as a chromophore, and a pH-sensitive piperazine moiety was inserted into it along with an FAsensitive primary amine moiety to produce FAHCy-FAH + (Figure 19). 41 Upon reaction with FA, HCy1 showed a color change from blue to green in a weakly acidic environment (pH 3−6); in contrast, it stayed blue in basic or neutral conditions.…”

“…This new solution then exhibited a peak at 582 nm, whereas the intensity of the peak at 475 nm was reduced (Figures and ) . The former probe has a lower LOD with 30 μM (0.03 M) than the CHA probe (0.20 M) …”

Reaction-based fluorescent and chemiluminescent probes for formaldehyde detection and imaging

“…Probe 5 was prepared as a paper strip whose color changed from yellow to red and fluorescence quenching could be observed by naked eyes when exposed to FA. 40 Based on the fluorophore of 7-nitrobenz-2-oxa-1,3-diazole (NBD), Mahapatra et al employed 2-aminoethyl piperazine as the donor group and amine group as the recognition unit to sensing FA (6). 41 After the formation of the imine group with FA, the PET effect from the nitrogen lone pair of primary amine moiety to the NBD moiety was inhibited and the fluorescence increased sharply as well.…”

Optimization of coastal land in Modung District, Bangkalan Regency as a conservation effort

“…Coastal erosion and its management have been the focus of recent research. Not only global climate change, erosion in coastal areas is also caused by a reduction in the amount of river sediment due to sand mining and dam construction, land conversion, disruption of sediment transport along the * Corresponding author: maulinnakusumo@trunojoyo.ac.id coast due to coastal structures and other anthropogenic activities [4][5].…”