Study of Linear and Nonlinear Optical Properties of Four Derivatives of Substituted Aryl Hydrazones of 1,8-Naphthalimide

A Naked Eye and Fluorescence Turn-on Sensor for Smartphone Assisted Solid and Solution Phase Sensing of Highly Toxic Triphosgene

A naked eye and fluorescence turn-on 1,8-naphtahlimide based chemosensor,1, possessing Schiff base linkage was utilized for the rapid detection of highly toxic triphosgene. The proposed sensor selectively detected triphosgene over various other competitive analytes including phosgene with the detection limit of 6.15 and 1.15 µM measured using UV-vis and fluorescence spectrophotometric techniques, respectively. Colorimetric changes observed in solution phase were processed by image analysis using smartphone leading to on-site and inexpensive determination of triphosgene. Further, solid phase sensing of triphosgene was carried out by 1 loaded PEG membranes and silica gel.

Naphthalimide-Based Hydrazone Derivatives: Synthesis, Mechanochromism in the Solid State and Response to Ions in Dilute Solutions

Molecules showing mechanochromic luminescence (MCL) are promising for use in the in the fields of sensing and probes. We report the design and synthesis of new naphthalimide-based hydrazone derivatives, NI-TPE and NI-3BA. Both the luminogens are weakly emissive with ^s Φ_f =0.3 % and 0.5 % respectively when aggregated in amorphous states as strong π-π stacking and intermolecular interaction prevent luminescence. On the contrary, in the crystalline state, single crystal analysis of two derivatives shows that nonradiative decay is reduced or inhibited by molecular stacking modes and intermolecular interactions. Increases of fluorescence emission intensity to ^s Φ_f =5.5 % and 6.0 % upon solvent evaporation are attributed to weak π-π overlapping and hydrogen bonding (N-H ⋅⋅⋅ O, distance 2.99 Å), which are beneficial to the formation of molecules with a loose packing. At the same time, the packing modes that the two derivatives adopt in the crystal lattice are destroyed to result in a low solid-state fluorescence quantum yield and a bathochromic shift of 23-25 nm upon grinding. All these factors cause the two derivatives show an unusual "turn off" MCL phenomenon. The fluorescence emission, its pH reversibility, and selective response to fluoride and acetate ions of up to 91-93 % in dilute solutions were also demonstrated.

Reusable colorimetric and fluorescent chemosensors based on 1,8-naphthalimide derivatives for fluoride ion detection

Two 1, 8-naphthalimide derivatives, 2-(2-ethylhexyl)-6-(2-(4-(5-phenyl-1,3,4-oxadiazol-2-yl)benzylidene)hydrazinyl)-1H-benzo[de]isoquinoline-1,3(2H)-dione (named as NAOZ) and 2-(2-ethylhexyl)-6-(2-(4-(5-phenyl-1,3,4-thiadiazol-2-yl)benzylidene)hydrazinyl)-1H-benzo[de]isoquinoline-1,3(2H)-dione (named as NATZ), containing hydrazone and thiadiazole/oxadiazole, were successfully synthesized. Compounds NAOZ and NATZ were further served as efficient reversible colorimetric and fluorescent chemosensors for fluoride ion over a wide range of other anions (Cl^-, Br^-, I^-, NO₃^-, ClO₄^-, HSO₄^-, BF₄^-, and PF₆^- as their (C₄H₉)₄N⁺ salts) because fluoride ion can deprotonate the hydrazone moiety, leading to the observed long-wavelength color change. Interestingly, CO₂ can recover the charge transfer (CT) absorption and photoluminescence intensities of compound NAOZ/NATZ + F^-, because CO₂ can react with a small amount of water to form acids, which can provide protons.

P. N, Keloth C, Wolcan E, D UK. Facile synthesis and exploration of excited state assisted two-photon absorption properties of D–A–D type thiophene–pyridine derivatives

Diagrammatic representation of excited state assisted two-photon absorption (2PA) behavior of a donor–acceptor type conjugated polymer (P2TPy) exhibiting an extremely low optical limiting threshold.

Isatin-1,8-Naphthalimide Hydrazones: A Study of Their Sensor and ON/OFF Functionality

Five novel hydrazones derived from substituted isatins were synthesized as potential anion sensors. Using UV-VIS, FTIR, NMR and fluorescence spectroscopy, these compounds’ tautomeric equilibrium and Z-E photoisomerization were studied in DMF and CHCl₃, depending on the hydrazone concentrations, the presence of basic anions and light stimulation. Anion recognition aspects (PF₆⁻, HSO₄⁻, Br⁻, Cl⁻, NO₃⁻, F⁻ and CH₃COO⁻) and these receptors’ detection limits were also studied. We also tested the light-stimulated ON-OFF functionality of these compounds in the presence or absence of these anions.

UK, P. P. N, Chandrasekharan K. Effects of substituents on the enrichment of the optical limiting action of novel imidazo[2,1-b][1,3,4]thiadiazole fused thiophene-based small molecules

Schematic of the optical limiting action of a novel imidazo[2,1-b][1,3,4]thiadiazole based small molecule (ThITD3), which blocks high irradiance and transmits low-intensity (less harmful) light.