Abstract
A simple strategy is proposed to design and develop an intelligent device based on dual channel ion responsive spectral properties of a commercially available molecule, harmine (HM). The system can process different sets of opto-chemical inputs generating different patterns as fluorescence outputs at specific wavelengths which can provide an additional level of protection exploiting both password and pattern recognitions. The proposed system could have the potential to come up with highly secured combinatorial locks at the molecular level that could pose valuable real time and on-site applications for user authentication.
Highlights
Harmine (HM) in Fig. 1 was used in the present work
The sequential logic operations enable us to fabricate a binary logic gate which can work as a molecular keypad lock with three inputs (F− ions, HSO4− ions and 300 nm UV radiation, symbolized as “F”, “H” and “U”, respectively), and dual fluorescence outputs
In case of UFUHU password entry in pure ACN when the first three inputs (U, F & U; UFU) are inserted sequentially instantaneously one would observe the fluorescence intensity diminished at 365 nm and augmented at 415 nm (Figs 3a and 5a)
Summary
Harmine (HM) in Fig. 1 was used in the present work. It is a compound fabricated from a common tricyclic system, with dual hydrogen bonding sites at the adjacent positions. In case of mixed solvents, upon titration with HSO4− ions resulted in quenching of fluorescence at 365 nm, acting as an “OFF” switch (Fig. 2b). In case of ACN-Water mixture, the same IMPLY gate can be operated with the direct NAND and NOT input channels reversed between F− and HSO4−.
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