Ag Interactions Research Articles

Nickel(II) and Copper(II) Dicyanoargentate Complexes with Ethylenediamine and 4,4´-Bipyridyl Ligands

The reactions of an aqueous solution of potassium dicyanoargentate with a mixture of nickel(II) or copper(II) chloride and ethylenediamine or 4,4´-bipyridyl in ethanol afford coordination polymers [Ni(En)2(Ag(CN)2)][Ag(CN)2] (I), [Cu(En)2(Ag(CN)2)][Ag(CN)2] (II), and [Cu(4,4´-Bipy)2(Ag(CN)2)2] (III) characterized by XRD (CIF files CCDC nos. 2225984 (I), 2214320 (II), and 2229270 (III)) and IR spectroscopy. According to the XRD data, the crystals of complexes I and II are formed by 1D chains {··NC– Ag–CN–M(En)2··}n (M = Ni (I), Cu (II)) linked with each other by the dicyanoargentate anions via argentophilic contacts (Ag···Ag 3.288(8) Å (I), 3.1616(14) Å (II)). The crystal of compound III consists of independent interpenetrating 3D networks built of polymer layers {Cu[Ag(CN)2]2}n bound to each other by the 4,4´-bipyridyl molecules. The bipyridyl linkers connect the Cu centers with the Ag centers of the [Ag(CN)2]– anions thus providing the tridentate coordination of the silver atoms. No Ag···Ag interactions are observed in the crystal of complex III.

Origin of Au-Ag Mineralization in Sphalerite Ores from Data on Sphalerite Co-Crystallization with Ag and Au in Model Hydrothermal Systems

Abstract ––Au-Ag mineralization occurrences in sphalerite ores of hydrothermal genesis are paradoxical in view of the incompatibility of these elements in sphalerite. The formation of sphalerite with Au and Ag impurities under hydrothermal crystallization of ZnS at 450 °C and 1 kbar pressure was studied experimentally. Sn impurity was taken as a source of point defects in crystals modelling the interaction of Au and Ag with vacancies. The Ag solubility in low-Fe sphalerite is estimated as 3.8 ± 0.7 μg/g, Au ̶ ≤ 0.6 μg/g. The main forms of Ag and Au occurrence in sphalerite are the inclusions of (Ag, Au)xS phases with x varies mainly from 1.8 to 2.0, and Au varies from 0.01 to 0.75 a.p.f.u. The primary forms of the elements in ores might be microinclusions (Ag, Au) 1.8-2.1S or close to (Ag, Au)S at higher fS2. In presence of Sn, solubilities of Au and Ag become higher. The behavior of Au corresponds to the substitution reaction Sn4+ + Au+ + v‒ ↔ 2Zn2+ in the presence of two types of vacancy defects (v–) ‒ the “inherent” vacancies dependent on the crystallization conditions and the vacancies accompanying Sn4+ incorporation. Ag entrance is seemingly more dependent on fS2 conditions and does not correlate with Sn. The extra vacancies arise because of metastable crystallization under the conditions of oversaturation of growth medium. This is supported by the spherulite morphology of growth products and the admixture of wurtzite ZnS form. The distribution and cocrystallization coefficients show an increasing trend for both precious metals (PM), due to which Au changes from incompatible to the category of highly compatible elements in sphalerite. The geochemical environments favorable for the formation of imperfect mineral crystals are considered. Such crystals are capable to uptake PMs and other incompatible in “ideal” crystal elements because of their interaction with vacancies, both constitutional (inherent to the substance) and non-equilibrium defects, and surficial nano-sized formations (nonautonomous phases). The evolution of these initially “invisible” forms of PM under metamorphic processes and remobilization of ore substance may result in Au and Ag escape and aggregation into microparticles.

Synthesis, characterization and computational studies of the triangle shape complex of silver nitrate with 2-amino-1,3,4-thiadiazole

A new mononuclear salt-like silver(I) complex [AgL3]NO3 (Complex 1), which was readily fabricated from 2-amino-1,3,4-thiadiazole (L), is reported. Complex 1 was analyzed by elemental analysis, FT-IR and UV–vis spectroscopy, and single crystal X-ray diffraction. Intermolecular contacts for the cation [AgL3]+ in the crystal structure of Complex 1 were examined using the Hirshfeld surface analysis. The DFT-based calculations were additionally applied to reveal electronic features of Complex 1. The molecular structure of Complex 1 exhibits a mononuclear planar cation [AgL3]+ of the triangle shape with three ligands L being monocoordinated through thiadiazole the nitrogen atom, located at the third position. Two cations [AgL3]+, which, in turn, are stabilized by three NH⋯N hydrogen bonds, are stacked through a rich variety of noncovalent interactions formed by the thiadiazole π-system, yielding a supramolecular dimer {[AgL3]2}2+. These dimers are linked through Ag⋯Ag interactions with the formation of a 1D supramolecular cationic pillar {[AgL3]n}n+. A solution of Complex 1 in EtOH absorbs in the UV region due to intraligand transitions within L. Theoretical calculations revealed a strong electrophilic nature of the optimized structure of Complex 1.

Synthesis and characterization of tetrapodal nickel complexes with adaptable ligand binding geometries.

This study explores the versatile binding properties of a tetrapodal ligand framework with nickel, demonstrating significant ligand fluxionality through the interconversions of several complexes. Kinetic studies using UV-vis and NMR techniques underscore the pivotal role of solvent coordination in initiating these dynamic processes. A unique reverse-dative Ni → Ag interaction provides another approach in modifying nickel's geometry.

N,N-dibenzyl dithiocarbamato silver(I) as precursor for silver sulfide nanophotocatalysts for photocatalytic degradation of rhodamine 6G and trypan blue dyes

N,N-dibenzyl dithiocarbamate silver(I) was synthesized and characterized by spectroscopic techniques and single crystal X-ray crystallography. The complex crystallizes in the trigonal space group P31 to form a one-dimensional, chain-like polymeric structure connected by Ag-Ag argentophilic and Ag-S interactions. The complex was used as single source precursor and thermolyzed at 120, 160 and 200 °C in 1-dodecanethiol to prepare silver sulfide nanoparticles (AgS-120, AgS-160 and AgS-200). TEM images showed quasi-spherical nanoparticles with average particle sizes of 4.0, 5.4 and 5.5 nm for nanoparticles prepared at 120, 160 and 200 °C, respectively, with optical band gaps of 3.76, 3.81 and 3.71 eV. The as-prepared silver sulfide nanoparticles potential as photocatalysts were evaluated using rhodamine 6G and trypan blue under irradiation. The photocatalytic degradation efficiency of 42.4% (k = 3.03 × 10−3), 41.9% (k = 2.73 × 10−3) and 56.7% (k = 4.16 × 10−3) for rhodamine 6G dye and 35.4% (2.94 × 10−3), 49.7% (3.87 × 10−3) and 16.9% (9.0 × 10−4) for trypan blue dye were obtained in the presence of AgS-120, AgS-160 and AgS-200, respectively. The kinetics and mechanism of photocatalytic reaction show that the dye degradation in the presence of the as-prepared nanoparticles follow pseudo-first order kinetics.

Hybrid silver(I) coumarin-carbene and coumarin-triphenylphosphine complexes: Towards more effective antimicrobial therapies

The rise of antimicrobial resistance and the resulting societal burden has highlighted the need for the development of novel therapeutics. Towards that end, a series of hybrid silver(I) coumarin-carbene and coumarin-triphenylphosphine complexes were synthesised and characterised by spectroscopic analysis including IR, 1H and 13C NMR spectroscopy, elemental analysis, and X-ray crystallography. Isolation of coumarin-carbene hybrid complexes was achieved using two methods, with isolation via firstly the in-situ generation of a free carbene under Schlenk conditions, followed by reaction with a coumarin silver(I) complex resulting in the formation of a hybrid complex with two silver ions forming a strong argentophilic Ag(I)–Ag(I) interaction. In this hybrid complex one silver(I) ion was bound to two coumarin carboxylate ligands with the other ion bound to two carbene ligands. Isolation via an ionic carbene route led to more complex aggregates but both types of complexes had good solubility and photostability as did the triphenylphosphine hybrid complexes. All the hybrid complexes showed therapeutic potential as antimicrobial agents against MRSA with the carbene hybrid complexes exhibiting an increased antimicrobial activity against both E. coli and MRSA when compared to the initial silver(I) complexes.

Exploring the Nature of Ag–Ag Interactions in Different Tellurides by Means of the Crystal Orbital Bond Index (COBI)

Exploring the Nature of Ag–Ag Interactions in Different Tellurides by Means of the Crystal Orbital Bond Index (COBI)

Effect of M-site element on the interaction of M2AlC and Ag and the induced properties of Ag/M2AlC composites

The deintercalation of weakly bonded A element affects the microstructure and properties of MAX phases and their reinforced composites. In this work, the effect of M-site element on the interaction of Al-containing M2AlC (M = V, Cr) phase and Ag, and the induced properties of Ag/M2AlC electrical contact materials (ECMs) were investigated. Though Ag and Al are soluble to each other and can form intermetallics, the variation of M element significantly affected the vacancy formation of Al, and thereby the interfacial reaction of Ag/M2AlC. The difficult formation of Al vacancy in V2AlC contributed to no obvious interfacial reaction in Ag/V2AlC. But the easy deintercalation of Al atoms in Cr2AlC led to their massive replacement by Ag, which generated Ag nano-twins and Cr3C2 with the same crystallographic relationship in one original Cr2AlC, and Cr7C3 and Ag3Al as well. Due to the distinct interactions, the resistivities of Ag/V2AlC and Ag/Cr2AlC increased by roughly 1 and 5 times after sintering, respectively. The low resistivity and proper hardness of the sintered Ag/V2AlC, which were very close to those of the “all-purpose” commercial Ag/CdO, contributed to its superior arc erosion resistance.

Element-specific cluster growth on the two-dimensional metal–organic network

A porous two-dimensional metal–organic network (2D-MON) on a substrate captures deposited metal atoms and metal clusters growing in the pores of the 2D-MON. We found that the growth mechanisms of Ag, In, and Pd clusters in the 2D-MON synthesized from 1,3,5-tris(4-bromophenyl)benzene molecules on Ag(111) are different from each other, and the difference derives from the interaction of an adatom with the 2D-MON. Ag and Pd clusters grow from the 2D-MON since the interaction of Ag and Pd adatoms with the 2D-MON is attractive. In clusters grow inside of the pores of the 2D-MON since the interaction between an In adatom and the 2D-MON is repulsive. The growth process of metal clusters is determined by the element-specific behavior of metal adatoms in the pores, taking into account interactions with the 2D-MON.

Important Counteranion Effect on Adsorption Efficacity of Hydrogen Sulfide by Silver(I)-Dithione Coordination Polymers.

Four new coordination polymers (CPs) have been prepared and evaluated for their efficacy in adsorbing hydrogen sulfide. The reactions of the structurally flexible assembling dithione ligand, L, with different silver(I) salts lead to four new metal-organic coordination architectures (CPs I, III, V, and VIII) exhibiting either one- or two-dimensional networks. CP I, 2D-[(Ag2Cl2)L]n, exhibits a linear series of rhomboid (S)2Ag(μ2-Cl)2Ag(S)2 secondary building units (SBUs) where S is one of the thione functions of L, altogether forming a 2D-network. CP III, 2D-[(AgI)L]n, is built upon parallel staircase-shaped 1D-[Ag2(μ3-I)2]n SBUs bridged by S atoms of L that form a 2D-grid. CP V, 2D-[(AgL)(NO3)]n, presents parallel 1D-folded S-shaped [AgL]n+ chains linked by strong argentophilic Ag···Ag interactions, forming a 2D-scaffolding. CP VIII, 1D-[(Ag2L3)(Cr2O7)]n, shows 1D-zigzag [{Ag(η2-μ2,η-μ,μ-L)}2]n2n+ chains accompanied by Cr2O72- counteranions. The adsorption isotherms of H2S gas by these new CPs were examined and compared to those of related CPs [(Ag2Br2)L]n (II), [(AgCN)4L]n (IV), [(Ag2L)(CF3SO3)2]n (VI), and [(Ag2L)(NO3)(ClO4)]n (VII). Among the tested polymers, the 3D-CP IV featuring cyanide anions exhibits the highest adsorption capacity of the CPs studied in this work. In order to determine the reason for this marked difference, density functional theory (DFT) computations were used. All in all, it turns out that the electrostatic interactions (CN-···H-SH) are significantly stronger than the O-···H-SH ones. This investigation provides a valuable conceptual tool for other designs of CPs and MOFs having the purpose of capturing toxic gases.

Adsorption of Pb(II) and Ag(I) using iron/manganese oxides modification biochar

The iron/manganese oxides modification biochar (Mn/Fe-biochar) is prepared by pyrolysis of RS impregnated with KMnO4 and Fe(NO3)3 for Pb(II) and Ag(I) removal from wastewater. Pb(II) and Ag(I) adsorption process on Mn/Fe-biochar are exactly analyzed using the Pseudo-second order and Hill model. Pb(II) and Ag(I) adsorption capacity of Mn/Fe-biochar are 88.49 and 134.80 mg/g based on Hill model, respectively. Adsorption thermodynamics analysis indicates the feasible and spontaneous Pb(II) and Ag(I) adsorption on Mn/Fe-biochar. Adsorption mechanism analysis indicates that π-π interaction and surface functional groups contribute to Pb(II) and Ag(I) removal. Density functional theory calculation indicates that binding energies of Pb(II) and Ag(I) interactions with -Mn-O group are the largest than that of the -OH, -COOH, -Fe-O groups, indicating that -Mn-O group plays an important role in Pb(II) and Ag(I) adsorption process. Reusability analysis indicates that Mn/Fe-biochar still has high Pb(II) and Ag(I) adsorption capacity after three cycles. The preliminary economic analysis indicates that the production cost of the Mn/Fe-biochar is estimated as the $4.94/1 kg.

Electrocatalytic and photocatalytic activities of two alkynyl Ag20 cage clusters involved ligand exchange between PhCOO− and CF3COO−

Two silver alkynyl clusters, [(CO32−)@Ag20(tBuC≡C)14(PhCOO)3(CF3COO)] (1) and [(CO32−)@Ag20(tBuC≡C)14(PhCOO)(CF3COO)3] (2), composed of alkynyl Ag20 shell templated by a CO32− anion and supported by carboxyl ligands PhCOO− and CF3COO−, were synthesized successfully by conventional methods. Single crystal X–ray diffractometer (SCXRD) was used to determine the precise structures of 1 and 2. Although compounds 1 and 2 have the [(CO32−)@Ag20(tBuC≡C)14]4+ unit, the numbers of PhCOO− and CF3COO− ligands along with Ag···Ag interactions were affected by the steric hindrance of different carboxyl ligands and their concentrations. That is, compounds 1 and 2 separately contain the [(CO32−)@Ag20(tBuC≡C)14(PhCOO)(CF3COO)]2+ unit, which is involved in the ligand exchange between PhCOO− and CF3COO−. Powder X-ray diffraction (PXRD), fourier transform infrared spectroscopy (FT-IR), and thermogravimetric analysis (TGA) were used to characterized compounds 1 and 2. The photocurrent responses, absorption spectra, as well as luminescence of 1 and 2 have been studied. In addition, the reduction of H2O2 for GCE–1 and GCE–2 showed good electrocatalytic activity, and catalysts 1 and 2 showed good photocatalytic degradation efficiency of methylene blue (MB). The results suggest that 1 and 2 can act as new electrocatalysts and photocatalysts to detect and decompose organic pollutants and hazardous materials in wastewater.

The X-ray peak profiling, optical and dielectric properties of Ag@ZnFe2O4/rGO ternary nanocomposites: LED assisted photocatalysis and humidity sensing

Ag@ZnFe2O4/reduced graphene oxide (Ag@ZnFe2O4/rGO) ternary nanocomposites were successfully synthesized (NCs) via hydrothermal method and explored the LED assisted photocatalytic performance for the degradation of organic dyes as well as humidity sensing properties of the material. For comparison, bare ZnFe2O4, and ZnFe2O4/rGO also synthesized. The freshly prepared samples were investigated using XRD, TEM, UV–vis–NIR spectroscopy, VSM, Impedance analyzer, and particle size analyzer. The detailed structural parameters were calculated through X-ray peak profiling using Classical Scherrer, Modified Scherrer, Williumson-Hall, Halder-Wagner, Size Strain Plot methods along with Rietveld refinement. From UV–vis–DRS analysis, optical energy gaps were obtained in the range of 1.58–1.92 eV. Ag@ZnFe2O4/rGO NCs showed significant photocatalytic activity and exceptional adsorption capacities for the breakdown of methylene blue (MB) 95.7% and rhodamine B (RhB) 77.7% after 100 min. The synergistic interactions of Ag, ZnFe2O4, and rGO minimized NCs agglomeration and small particle size with higher surface area, resulting in a higher absorption in both UV and visible light. The photocatalysis mechanism was explored by scavenger test using ascorbic Acid, NaHCO3, and isopropyl alcohol. The magnetic studies revealed the paramagnetic nature of NCs. Frequency dependent dielectric data obey the modified Debye model with relaxation time of ∼10−4 s and spreading factor of 0.534 (±0.08). Complex impedance measurements support the grain-interior process that contributes to dielectric properties. The impedance-type humidity sensing characteristics of the fabricated sensor were investigated by exposing in a wide humidity range of 11–98% RH at ambient temperature. The Ag@ZnFe2O4/rGO sensor displayed an ultrahigh sensitivity when compared to traditional humidity sensors. On the basis of, Ag@ZnFe2O4/rGO NCs are exciting nanomaterials for outstanding photocatalytic activity for the degradation of organic dyes along with potent humidity sensor.

Cyclometalated luminescent platinum(II) complexes of dissymmetrical 2,2':4',2''-terpyridine and its self-assembled dimer presenting Pt-Ag dative bonds.

A series of cyclometalated (N^C^N) Pt(II)-platinum complexes featuring a terpyridine ligand with a non-coordinating nitrogen atom and a Pt-C bond was synthesized. In the presence of Ag+, the bis(isonitrile)Pt(II) complex formed a remarkable self-assembled helicoidal dimer stabilized by coordination of Ag(I) and metallophilic Pt-Ag interactions. Its assembly was observed in the solid state and maintained in solution. All complexes show strong luminescence and multiple emitting states, which could be rationalized based on solid state X-ray structures and coordinating environment.

Silver ion-regulated reliable and rapid detection technique for alkaline phosphatase based on surface-enhanced Raman spectroscopy.

The primary characteristics of a clinical assay are its accuracy and speed. For alkaline phosphatase (ALP) monitoring in medical treatment, a rapid, reliable surface-enhanced Raman scattering (SERS) detection technique was designed based on the controlled "hot spot" effect caused by the mediation of silver ions (Ag+). Consisting of functionalized Au nanoparticles (NPs), Ag+, and the enzyme substrate 2-phospho-L-ascorbic acid triso-dium salt (AAP), the fabricated detection technique can achieve a reliable clinical assay for ALP detection in human serum within several minutes. Herein, due to the coordination interaction of Ag+ and the cyano group (-CN), Ag+ can coordinate with p-mercaptobenzonitrile (MBN) modified on the surface of Au NPs, leading to the connection of adjacent Au NPs in a controllable manner to form a chain structure, in which the SERS signal of MBN at 2228 cm-1 in the Raman silent region would be highly amplified. Under the enzymatic biocatalysis of ALP, AAP was converted into ascorbic acid (AA). AA triggered the reduction of Ag+ into Ag0, resulting in a decrease in the concentration of Ag+. Meanwhile, the decrease in the SERS intensity of MBN was well-controlled and was recognized with the increased amounts of ALP. Based on this, the SERS detection technique for ALP was established. The limit of detection (LOD) for the detection of ALP was as low as 1.23 pg mL-1 (0.005 U L-1). Because of all these characteristics and its ultrahigh stability, this SERS detection technique is an important point-of-care candidate for the reliable, efficacious, and highly sensitive detection of ALP.

Cu2O/Ag-coated wood-based biochar composites for efficient adsorption/photocatalysis synergistic degradation of high-concentration azo dyes

In order to effectively eliminate organic azo dyes with high concentrations from aqueous environments, novel adsorption/photocatalysis composites were prepared using Cu2O/Ag-coated carriers based on renewable wood-based biochar (MBC). The adsorption process of the prepared MBC@Cu2O/Ag-3 under electrostatic attraction, hydrogen bonding, and complexation effects was conformed to the proposed second-order kinetic model, and the total sorption capacity of Congo red (CR) and methyl orange (MO) reached 264.55 and 178.63 mg g−1, respectively. Moreover, the coordinated interaction of MBC, Cu2O, and Ag enhanced the visible light absorptivity, which further facilitated the effective dissociation of light-generated electrons from holes. The removal rates of CR and MO by MBC@Cu2O/Ag-3 in the presence of visible light were up to 98.4 % and 97.8 %, respectively. In addition, free radical capture and electron spin resonance (ESR) spectroscopy analyses indicated that superoxide (·O2-) and hydroxyl (·OH) radicals were major activators during the photocatalytic progression, and the adsorption/photocatalysis mechanism was elucidated through a series of characterization experiments. This work shows that the utilization of natural biomass materials for the preparation of adsorption/photocatalysis composites with high added value can significantly contribute to water environmental protection and sustainable development.

Dual-Channel Fluorescent/Colorimetric-Based OPD-Pd/Pt NFs Sensor for High-Sensitivity Detection of Silver Ions.

Silver ions (Ag+) exist widely in various areas of human life, and the food contamination caused by them poses a serious threat to human health. Among the numerous methods used for the detection of Ag+, fluorescence and colorimetric analysis have attracted much attention due to their inherent advantages, such as high sensitivity, simple operation, short time, low cost and visualized detection. In this work, Pd/Pt nanoflowers (NFs) specifically responsive to Ag+ were synthesized in a simple way to oxidize o-phenylenediamine (OPD) into 2,3-diaminophenazine (DAP). The interaction of Ag+ with the surface of Pd/Pt NFs inhibits the catalytic activity of Pd/Pt NFs towards the substrate OPD. A novel dual-channel nanosensor was constructed for the detection of Ag+, using the fluorescence intensity and UV-vis absorption intensity of DAP as output signals. This dual-mode analysis combines their respective advantages to significantly improve the sensitivity and accuracy of Ag+ detection. The results showed that the limit of detection was 5.8 nM for the fluorescence channel and 46.9 nM for the colorimetric channel, respectively. Moreover, the developed platform has been successfully used for the detection of Ag+ in real samples with satisfactory recoveries, which is promising for the application in the point-of-care testing of Ag+ in the field of food safety.

Structural, spectroscopic, and chemical bonding analysis of luminescent bis(diphenylphosphino)methane derived binuclear heteroleptic silver(I) complex of norharmane with argentophilic interaction

Silver(I) coordination compounds have a fascinating geometrical diversity, the ability to have different coordination numbers (typically from 2 to 4), and the ability to form argentophilic (Ag∙∙∙Ag) interactions. In this work, a binuclear Ag(I) heteroleptic complex with norharmane ‘β-carboline’ and bis(diphenylphosphino)methane (PP) ligands has been synthesized and characterized by various spectroscopic and single-crystal X-ray diffraction analyses. The bonding of Ag(I) coordination and Ag···Ag interaction is explored in depth. The theoretical approaches employed were perturbation theory within the context of the natural bond orbital (NBO) framework, quantum theory of atoms in the molecule (QTAIM), and electron localization function (ELF) analysis.

Luminescent heterobimetallic Au(I)/Ag(I) complex stabilized by a unique acetylide fragment: A spectroscopic and computational study of aurophilic ‒ argentophilic interactions

This paper investigates the luminescence and metallophilic interaction in the heterobimetallic Au(I)-Ag(I) acetylide cluster [Au2Ag2(CCPh)4(PPh3)2]. Analysis using single-crystal X-rays shows short Au∙∙∙Ag separations (2.8806(3)-3.0212(3) Å), showing favorable closed shell (d10⋯d10) aurophilic-argentophilic interactions. DFT calculations and ELF analysis reveal electron localization between Au⋯Ag contacts and electron density dispersion around gold and silver ions. Quantum Theory of Atoms in Molecules (QTAIM) research reveals electron density at bond critical points (bcp) and assesses Au(I)⋯Ag(I) interaction strengths. Natural Bond Orbital (NBO) analysis identifies donor–acceptor characteristics of orbitals involved in aurophilic ‒ argentophilic interactions.

SARS-CoV-2 antibodies recognize 23 distinct epitopic sites on the receptor binding domain

The COVID-19 pandemic and SARS-CoV-2 variants have dramatically illustrated the need for a better understanding of antigen (epitope)-antibody (paratope) interactions. To gain insight into the immunogenic characteristics of epitopic sites (ES), we systematically investigated the structures of 340 Abs and 83 nanobodies (Nbs) complexed with the Receptor Binding Domain (RBD) of the SARS-CoV-2 spike protein. We identified 23 distinct ES on the RBD surface and determined the frequencies of amino acid usage in the corresponding CDR paratopes. We describe a clustering method for analysis of ES similarities that reveals binding motifs of the paratopes and that provides insights for vaccine design and therapies for SARS-CoV-2, as well as a broader understanding of the structural basis of Ab-protein antigen (Ag) interactions.