α-Amino Acid Derived Benzimidazole-Linked Rhodamines: A Case of Substitution Effect at the Amino Acid Site toward Spiro Ring Opening for Selective Sensing of Al³⁺ Ions

Abstract

α-Amino acid derived benzimidazole-linked rhodamines have been synthesized, and their metal ion sensing properties have been evaluated. Experimentally, l-valine- and l-phenylglycine-derived benzimidazole-based rhodamines 1 and 2 selectively recognize Al ion in aqueous CHCN (CHCN/HO 4/1 v/v, 10 mM tris HCl buffer, pH 7.0) over the other cations by exhibiting color and "turn-on" emission changes. In contrast, glycine-derived benzimidazole 3 remains silent in the recognition event and emphasizes the role of α-substitution of amino acid undertaken in the design. The fact has been addressed on the basis of the single-crystal X-ray structures and theoretical calculations. Moreover, pink 1·Al and 2·Al ensembles selectively sensed F ions over other halides through a discharge of color. Importantly, compounds 1 and 2 are cell permeable and have been used as imaging reagents for the detection of Al uptake in human lung carcinoma cell line A549.

Visualisation of DCP, a nerve agent mimic, in Catfish brain by a simple chemosensor

“…However, while adding DCP at neutral pH the probe shows its deep pink color even at pH 8 (Fig. S 13 ) 39 , 40 , which demonstrates the practical applicability of the chemosensor.…”

New stable colored complex of Al3+ with 1',3',3'‐trimethylspiro[2H‐1‐benzopyran‐2,2'‐indoline] (BIPS)

“…Specifically, such compounds have been studied as dark or light‐controlled chemosensors for metal ions and Al 3+ in particular . There is always a demand for reliable and facile sensors for salts and compounds of Al …”

High throughput screening of a new fluorescent G-quadruplex ligand having telomerase inhibitory activity in human A549 cells

“…Then several aliquots of 50 µM in Benchmark buffer were prepared from this and stored at -20 °C for future use. Before the experiment, one aliquot was taken and heated at 95 °C for 5 min followed by chilled in Cell permeability and cell imaging by fluorescence microscope: The penetrations of C-992 in living and fixed cultured human cells were checked as per our earlier report [24]. In brief, human lung cancer A549 cells were grown on cover slips placed inside the Petri plate for 24 h. Then one set of the cover slip containing the adherent living cells was treated with 20 nM C-992 for 30 min in dark (without fixation).…”

“…In our case, it takes the same conformation as evident from the typical positive peak at 295 and 250 nm as shown in Fig 8. To observe the cellular uptake of this compound by the live-cell A549 under culture condition with and without using a fixative, we incubated the A549 cells in presence of a very low concentration (20 nM) of C-992 in PBS for 30 min at 37 °C as per our previous report [24,35,36]. Then the cell images were captured under bright field mode (data not Several reports showed that the G-quadruplex ligand can inhibit telomerase activity [35][36][37][38][39][40].…”