electrically modulated surface enhanced Raman scattering (e-SeRS) can be able to regulate the plasmon resonance peak of metal nanostructures, further improve the detection sensitivity of the SeRS substrate. However, the e-SeRS substrates require auxiliary equipment to provide the electrical potential, and most of them are non-flexible structure, which limits the application of E-SERS in the portable, in-situ and fast detection area. Here, we developed an electric field-modulated SERS substrate based on the piezoelectric effect by combining the PVDF (piezoelectric-modulated layer) and Ag nanowires (AgnWs) (SeRS active layer) and investigated the SeRS activity in experiment and theory. The enhanced electric field and the tunable plasmon resonance induced by the piezoelectric effect provide the additional enhancement for the SeRS signal. furthermore, we fabricated a SeRS active ring with a piezoelectric field-modulated substrate and achieved the in-situ detection of glucose with a non-invasive method. this work provided innovation for the e-SeRS and could greatly promote the development of the in-situ, wearable and intelligent sensors.

The excited state intramolecular proton transfer of four derivatives (FM, BFM, BFBC, CCM) of 3-hydroxychromone is investigated. The geometries of different substituents are optimized to study the substituent effects on proton transfer. The mechanism of hydrogen bond enhancement is qualitatively elucidated by comparing the infrared spectra, the reduced density gradient, and the frontier molecular orbitals. The calculated electronic spectra are consistent with the experimental results. To quantify the proton transfer, the potential energy curves (PECs) of the four derivatives in S0 and S1 states are scanned. It is concluded that the ability of proton transfer follows the order: FM > BFM > BFBC > CCM.

The photophysical and photochemical properties of the novel hydrazine sensor TAPHP and the TAPDP generated by the cyclization reaction of TAPHP with hydrazine are investigated using the density functional theory and time-dependent density functional theory. The results show that both the excited-state intramolecular proton transfer and intramolecular charge transfer can occur for TAPHP and TAPDP. Analysis of bond parameters and infrared vibrational spectra indicate that hydrogen bonds are enhanced in the first excited state, which is beneficial to excited-state intramolecular proton transfer. The strength of hydrogen bonds is also visualized by using the independent gradient model and topological analysis. The core-valence bifurcation index and bond critical point parameters are further employed to measure hydrogen bonds. The reaction path of proton transfer is obtained through the potential energy curves. The excitation of TAPHP and TAPDP is attributed to the charge transfer excitation, which is determined by the characteristics of the hole-electron distribution. The reaction site and product configuration are verified by atomic charge and 1 H-NMR spectra. The negative free energy difference indicates that the reaction between TAPHP and hydrazine can proceed spontaneously. In addition, the absorption and fluorescence spectra agree well with the experimental results, confirming that TAPHP is an excellent sensor of hydrazine.

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