scholarly journals Formation of Citrazinic Acid Ions and Their Contribution to Optical and Magnetic Features of Carbon Nanodots: A Combined Experimental and Computational Approach

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 770 ◽  
Author(s):  
Francesca Mocci ◽  
Chiara Olla ◽  
Antonio Cappai ◽  
Riccardo Corpino ◽  
Pier Carlo Ricci ◽  
...  
Keyword(s):  
Molecular Model ◽  
Chemical Shifts ◽  
Water Solution ◽  
Computational Approach ◽  
Carbon Nanodots ◽  
Surface Enhanced ◽  
Experimental Surface ◽  
Surface Enhanced Raman ◽  
Energy Formation ◽  
Ph Conditions

The molecular model is one of the most appealing to explain the peculiar optical properties of Carbon nanodots (CNDs) and was proven to be successful for the bottom up synthesis, where a few molecules were recognized. Among the others, citrazinic acid is relevant for the synthesis of citric acid-based CNDs. Here we report a combined experimental and computational approach to discuss the formation of different protonated and deprotonated species of citrazinic acid and their contribution to vibrational and magnetic spectra. By computing the free energy formation in water solution, we selected the most favoured species and we retrieved their presence in the experimental surface enhanced Raman spectra. As well, the chemical shifts are discussed in terms of tautomers and rotamers of most favoured species. The expected formation of protonated and de-protonated citrazinic acid ions under extreme pH conditions was proven by evaluating specific interactions with H2SO4 and NaOH molecules. The reported results confirm that the presence of citrazinic acid and its ionic forms should be considered in the interpretation of the spectroscopic features of CNDs.

Preparation of Au nano-particle dispersed water solution without surfactant for surface-enhanced Raman scattering platform

2017 ◽  
Vol 653 (1) ◽  
pp. 137-143 ◽  
Author(s):  
Naoki Matsuda ◽  
Tatsurou Nakashima ◽  
Hirotaka Okabe ◽  
Hiroshi Yamada ◽  
Hidenobu Shiroishi ◽  
...  
Keyword(s):  
Raman Scattering ◽  
Water Solution ◽  
Surface Enhanced Raman Scattering ◽  
Nano Particle ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Enhanced Raman Scattering

scholarly journals Raman and Fluorescence Enhancement Approaches in Graphene-Based Platforms for Optical Sensing and Imaging

Nanomaterials ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 644
Author(s):  
Sandra Cortijo-Campos ◽  
Rafael Ramírez-Jiménez ◽  
Alicia de Andrés
Keyword(s):  
Single Molecule ◽  
Fluorescence Enhancement ◽  
Carbon Nanodots ◽  
Special Focus ◽  
Noninvasive Methods ◽  
Light Enhancement ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Enhanced Raman Scattering

The search for novel platforms and metamaterials for the enhancement of optical and particularly Raman signals is still an objective since optical techniques offer affordable, noninvasive methods with high spatial resolution and penetration depth adequate to detect and image a large variety of systems, from 2D materials to molecules in complex media and tissues. Definitely, plasmonic materials produce the most efficient enhancement through the surface-enhanced Raman scattering (SERS) process, allowing single-molecule detection, and are the most studied ones. Here we focus on less explored aspects of SERS such as the role of the inter-nanoparticle (NP) distance and the ultra-small NP size limit (down to a few nm) and on novel approaches involving graphene and graphene-related materials. The issues on reproducibility and homogeneity for the quantification of the probe molecules will also be discussed. Other light enhancement mechanisms, in particular resonant and interference Raman scatterings, as well as the platforms that allow combining several of them, are presented in this review with a special focus on the possibilities that graphene offers for the design and fabrication of novel architectures. Recent fluorescence enhancement platforms and strategies, so important for bio-detection and imaging, are reviewed as well as the relevance of graphene oxide and graphene/carbon nanodots in the field.

Sign in / Sign up

Export Citation Format

Share Document