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SERS Spectra of the Pesticide Chlorpyrifos Adsorbed on Silver Nanosurface: The Ag20 Cluster Model
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2020-09-03 , DOI: 10.1021/acs.jpcc.0c06078 Thi Chinh Ngo 1, 2 , Quang Thang Trinh 3 , Nguyen Thi Thai An 1, 2 , Nguyen Ngoc Tri 4 , Nguyen Tien Trung 4 , Dinh Hieu Truong 1, 2 , Bui The Huy 5 , Minh Tho Nguyen 6 , Duy Quang Dao 1
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2020-09-03 , DOI: 10.1021/acs.jpcc.0c06078 Thi Chinh Ngo 1, 2 , Quang Thang Trinh 3 , Nguyen Thi Thai An 1, 2 , Nguyen Ngoc Tri 4 , Nguyen Tien Trung 4 , Dinh Hieu Truong 1, 2 , Bui The Huy 5 , Minh Tho Nguyen 6 , Duy Quang Dao 1
Affiliation
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Surface enhanced Raman scattering (SERS) experiments and quantum chemical calculations (using density functional theory) on the interactions of chlorpyrifos (CPF), which is an intensively used pesticide, with a roughed silver nanoparticle surface were thoroughly investigated to study the inherent molecular mechanism. Ligand–cluster interaction geometries show that the CPF molecule is mainly adsorbed on the silver surface via both S atom and pyridine ring involving a covalent Ag···S coordination as well as van der Waals physisorption. Raman vibrational modes of CPF are centered at 474, 632, 678, 1277, and 1551 cm–1 characterizing the P–O–C bending, P═S stretching, Cl-ring mode, and pyridine ring stretching, respectively, which are all enhanced when CPF is adsorbed on a silver surface. The concentration-dependent effect of CPF on silver substrates has been reproduced for the first time by coordinating 2 and 3 CPF molecules on an Ag20 silver cluster model simulated by DFT computations. The intensities of the characteristic peaks of CPF as shown in the calculated SERS spectra are increased by 2 and 3 times with respect to those of the CPF–Ag20 complex, which indicate a positive influence of high analyst concentration on the SERS signal. This observation can be explained by the electron-donating effect of CPF upon adsorption. The latter donates an electron from its lone pair on S and Cl atoms and a π electron on the S═P bond to silver atoms on the surface, and then the positive charge of silver surface is displaced to the CPF moiety via Ag···S and Ag···Cl contacts. The information obtained from the adsorption of CPF on silver by SERS is helpful to understand the molecular mechanism of adsorption process involving chlorpyrifos ligand coordinated on silver nanoparticle surfaces. It also contributes to design field detection methods for rapid screening and monitoring of pesticides in environment or agricultural products by using portable detection systems such as paper-based or fiber-based SERS sensors.
中文翻译：
银纳米表面上吸附的农药毒死rif的SERS光谱：Ag 20团簇模型
彻底研究了表面化学拉曼散射（SERS）实验和量子化学计算（使用密度泛函理论）对毒死py（CPF）与粗糙纳米银表面相互作用的毒死rif（CPF）的相互作用进行了研究，以研究其固有的分子机理。配体-团簇相互作用的几何结构表明，CPF分子主要通过S原子和吡啶环（共价Ag··S配位）以及范德华物理吸附作用同时吸附在银表面。CPF的拉曼振动模式集中在474、632、678、1277和1551 cm –1处当CPF吸附在银表面上时，分别表征了P–O–C弯曲，P═S拉伸，Cl环模和吡啶环拉伸，所有这些都得到增强。通过在DFT计算模拟的Ag 20银团簇模型上协调2和3个CPF分子，首次再现了CPF对银基质的浓度依赖性效应。计算出的SERS光谱中显示的CPF特征峰的强度是CPF-Ag 20的2和3倍复杂，这表明高浓度分析人员对SERS信号有积极影响。可以通过CPF在吸附时的供电子效应来解释这一观察结果。后者从其孤对上的一个S和Cl原子上提供一个电子，并在S═P键上将一个π电子提供给表面上的银原子，然后银表面的正电荷通过Ag···转移到CPF部分。 S和Ag···Cl接触。SERS从CPF吸附在银上获得的信息有助于理解涉及毒死rif配体在银纳米颗粒表面配位的吸附过程的分子机理。
更新日期：2020-10-02
中文翻译：
银纳米表面上吸附的农药毒死rif的SERS光谱：Ag 20团簇模型
彻底研究了表面化学拉曼散射（SERS）实验和量子化学计算（使用密度泛函理论）对毒死py（CPF）与粗糙纳米银表面相互作用的毒死rif（CPF）的相互作用进行了研究，以研究其固有的分子机理。配体-团簇相互作用的几何结构表明，CPF分子主要通过S原子和吡啶环（共价Ag··S配位）以及范德华物理吸附作用同时吸附在银表面。CPF的拉曼振动模式集中在474、632、678、1277和1551 cm –1处当CPF吸附在银表面上时，分别表征了P–O–C弯曲，P═S拉伸，Cl环模和吡啶环拉伸，所有这些都得到增强。通过在DFT计算模拟的Ag 20银团簇模型上协调2和3个CPF分子，首次再现了CPF对银基质的浓度依赖性效应。计算出的SERS光谱中显示的CPF特征峰的强度是CPF-Ag 20的2和3倍复杂，这表明高浓度分析人员对SERS信号有积极影响。可以通过CPF在吸附时的供电子效应来解释这一观察结果。后者从其孤对上的一个S和Cl原子上提供一个电子，并在S═P键上将一个π电子提供给表面上的银原子，然后银表面的正电荷通过Ag···转移到CPF部分。 S和Ag···Cl接触。SERS从CPF吸附在银上获得的信息有助于理解涉及毒死rif配体在银纳米颗粒表面配位的吸附过程的分子机理。
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