Browsing by Author "Isik Tasgin, Dilek"

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Citation - Scopus: 1
Pyrrolizine-3 Synthesis and Evaluation of Photophysical Properties
(Taylor & Francis inc, 2024) Tasgin, Dilek Isik; Bayraktar, Irem; Isik Tasgin, Dilek
We describe a synthetic approach for pyrrolizine-3-one derivatives and their photophysical properties. These compounds are prepared by a series of reactions employing the substituted pyrroles in one-pot, two-step oxidation, and intramolecular cyclization processes. The photophysical properties of the synthesized compounds were studied by using UV-Vis and fluorescence spectroscopy in different solvents. Maximum absorbance peaks were observed around 306-416 nm and maximum fluorescence emission around 603-614 nm and 465-498 nm for pyrrolyl and N-methyl pyrrolyl substituents, respectively. The introduction of a pyrrolyl substituent had a significant impact on the Stokes shifts (192-206 nm) and quantum yield values ranged from 0.002 to 0.046.
Citation - WoS: 1
Citation - Scopus: 1
Vertical Self-Assembly of Gold Nanoworms for Sensitive Surface-Enhanced Raman Spectroscopy-Based Trace Detection
(Amer Chemical Soc, 2025) Khan, Ghazanfar Ali; Demir, Ahmet Kemal; Demirtas, Ozge; Tasgin, Dilek Isik; Bek, Alpan; Bhatti, Arshad Saleem; Ahmed, Waqqar; Isik Tasgin, Dilek
The assembly of anisotropic nanoparticles into closely packed structures results in unique functionalities. Herein, we report a 3D multilayer vertical assembly of worm-shaped Au nanoparticles using a carefully regulated evaporation-induced deposition method. With the evaporation of the nanoworm (NW) suspension, the concentration of NWs in the suspension gradually increases, which generates a balance between electrostatic interactions and entropically driven attraction to produce multilayer vertical assemblies. These assemblies exhibit enhanced surface-enhanced Raman scattering (SERS) signals due to the presence of a high concentration of hotspots. Moreover, in contrast to nanorods, the bent morphology of NWs creates pores in the vertical assembly, enabling the analyte molecule to penetrate the assembly and access hotspots. Picomolar to micromolar concentrations of rhodamine 6G (R6G) were detected with the NW assembly-based SERS substrate with excellent linearity and uniformity of the signal with a spot-to-spot relative standard deviation (RSD) of only 8.9%. The SERS substrates were also employed for trace detection of ammonium nitrate, which is a well-known constituent of homemade explosives. Our method of producing multilayer vertical assemblies of NWs is simple, highly sensitive, stable, and reproducible for making effective SERS sensors for the quantitative detection of analytes.