Water-Soluble Pyrene-Adorned Imidazolium Salts with Multicolor Solid-State Fluorescence: Synthesis, Structure, Photophysical Properties, and Application on the Detection of Latent Fingerprints

Abstract

New water-soluble acetylpyrene-bound imidazolium salts (1- N -methyl-3-(2-oxo-2-(pyren-1-yl)ethyl)-imidazolium bromide ( 1 ), 1- N -isopropyl-3-(2-oxo-2-(pyren-1-yl)ethyl)-imidazolium bromide ( 2 ), 1- N -allyl-3-(2-oxo-2-(pyren-1-yl)ethyl)-imidazolium bromide ( 3 ), and 1- N -isopropyl-3-(2-oxo-2-(pyren-1-yl)ethyl)-imidazolium hexafluorophosphate ( 4 )) were synthesized from the reaction between 1-bromoacetylpyrene and N-substituted imidazoles in excellent yield. The new molecules were fully characterized by elemental analysis, FT-IR, multinuclear ( 1 H, 13 C, and 19 F) NMR techniques, and single-crystal X-ray diffraction analysis. Investigations on the crystal packing of 1 , 3 , and 4 show the presence of inter/intramolecular weak interactions, including the π···π stacking interaction between the pairs of pyrene molecules. The photophysical properties were investigated in detail for the four imidazolium salts. Experiments show that the emissions observed for all the four compounds are due to the excited monomer and static excimer. Very interestingly, all the four compounds exhibit solid-state multicolor fluorescence depending on the excitation wavelength. The solid-state emissions were monitored using a fluorescence microscope. Finally, a fingerprint powder was formulated based on compound 4 and demonstrated as an efficient fluorescent fingerprint powder for forensic applications. The formulated powder revealed all the 3 level information along with peculiar individual characteristics of the fingerprints under investigation. The fingerprints were further viewed through a fluorescence microscope, and the results were discussed in detail.

Tunable emission in the visible range from a single organic fluorophore through time-controlled morphological evolution

“…For most of the known pyrene derivatives, it has been reported that these exhibited mechanoflorochromism (MFC) and polymorphism as a result of changes in molecular packing in the crystal structure. 5,18,[48][49][50] So, we decided to study the effects of mechanical grinding on the newly synthesized derivative of pyrene-thiophene (PyS-Y). Many MFC materials transform from crystalline to amorphous under mechanical pressure due to the defects in the crystal packing, and revert to its original structure when heating the ground product or after fuming it with solvents.…”

Interpol review of fingermarks and other body impressions (2019 – 2022)

“…Preliminary/Pilot studies – Several compounds were presented as new dusting powders: AIE-active composites or molecules [ [277] , [278] , [279] , [280] , [281] ], algal biomass [ 282 ], anti-perovskite phosphors [ 283 ], azo-dyes [ 284 ], β-cyclodextrin-berberine complexes [ 285 ], benzazole derivatives [ 286 ], bisamide analogues [ 287 ], cadmium-doped silica microspheres [ 288 ], chitosan-tripolyphosphate-lysine conjugates [ 289 ], coumarin–pyridone conjugates [ 290 ], crushed eggshells and clamshells [ 291 ], crushed gambir [ 292 ], curcumin analogues [ 293 ], doped montmorillonite [ 278 , 294 , 295 ], doped starch microspheres [ [296] , [297] , [298] ], europium-dextrose composites [ 299 ], iron oxide/zinc sulphide hybrid [ 300 ], metal-organic frameworks [ 301 ], organic NIR emitters [ 302 , 303 ], perylenetetracarboxylate compounds [ 304 ], phenylthiazoles [ 305 ], phosphor-cellulose hybrids [ 306 ], pyrazoles [ 307 ], pyrene-tagged imidazolium salts [ 308 ], pyridine and pyrimidine derivatives [ 309 , 310 ], rare-earth-doped phosphors [ [311] , [312] , [313] , [314] , [315] , [316] , [317] , [318] , [319] ], reduced graphene oxides [ 320 ], resveratrol powder [ 321 ], rhodamine B-doped diatomaceous earth [ 322 ], Schiff base complexes [ [323] , [324] , [325] ], talcum powder […”

One molecule to light it all: The era of dual-state emission

“…p-p interactions upon crystallization, thus enhancing the solid-state emission. 7 Finally, the third feature, which is extremely useful for the technological application of these compounds, is based on the combination of strong push-pull intramolecular electronic effect. Joining electron-donating and electron-withdrawing components into a p-conjugated structure allows control over the Highest-Occupied Molecular Orbital (HOMO) and Lowest-Unoccupied Molecular Orbital (LUMO) energy levels.…”