Surface plasmon-polariton: a novel initiation way for azide alkyne

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Surface plasmon-polariton: a novel initiation way for azide alkyne cycloaddition Olga Guselnikova, Pavel S. Postnikov, Mohamed Mehdi Chehimi, Yevgeniya Kalachyova, Václav Švor#ík, and Oleksiy Lyutakov Langmuir, Just Accepted Manuscript • DOI: 10.1021/acs.langmuir.8b03041 • Publication Date (Web): 18 Jan 2019 Downloaded from http://pubs.acs.org on January 19, 2019

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Surface plasmon-polariton: a novel initiation way for azide alkyne cycloaddition Olga

Guselnikovaa,b,

Pavel

Postnikova,b*,

Mohamed

Mehdi

Ehdi

Chehimic,

Yevgeniya Kalachyovaa,b, Vaclav Svorcikb, Oleksiy Lyutakova,b* a

Department of Solid State Engineering, University of Chemistry and Technology, 16628 Prague,

Czech Republic b

Research School of Chemistry and Applied Biomedical Sciences, Tomsk Polytechnic University,

Russian Federation c

Université Paris Est, UMR 7182 CNRS, UPEC, 94320 Thiais, France

______________________ * Corresponding authors: [email protected], [email protected]

Abstract Plasmon-catalysis has recently generated tremendous interest in the field of modern chemistry. Application of plasmon introduces the principally new stimuli for the activation of organic reactions, keeping the optical energy concentrated in the vicinity of plasmonic structure, creating optical near-field enhancement as well as hot electrons injection. In this work, for the first time, we presented a new way for the initiation of the azide-alkyne cycloaddition (AAC) using the surface plasmon-polariton wave, supported by the gold grating. With this concept in hand, the plasmon-active gold grating was functionalized with the 4-ethynylbenzenediazonium compound. Then, surface grafted 4-ethynylphenyl groups were plasmon activated and clicked with 4azidobenzoic acid. Additional experiments excluded the potential effect of photon, heating, and metal impurities confirmed the key role of surface plasmon-polariton AAC activation. For investigation of plasmon-induced AAC mechanism, 4-azidophenyl groups (instead of 4ethynylphenyl groups) were also grafted to the grating surface. Further careful evaluation of reaction kinetics demonstrates that AAC reaction rate is significantly higher in the case of acetylene activation than in the case of azide activation. KEYWORDS: plasmon catalysis, surface plasmon-polariton, gold grating, surface modification, azide alkyne cycloaddition _____________________________

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Introduction The search of novel physical methods for the initiation of chemical transformations is considered to be one of the most important challenges in modern science for sustainable development and technology [1]. As main examples, the establishment of temperature, light, microwave or electrochemical reaction activation can be mentioned [2-7]. However, there is a continuous demand in the new methods for the initiation of chemical reactions, which are consistent with the timely requirements of applied science. Recently, a novel and extremely perspective way for the chemical processes activation was proposed: utilization of plasmon-based phenomena as the driving forces for chemical reactions [8-12]. Plasmon is the collective oscillation of electrons, excited by the external electro-magnetic wave on the metal-dielectric boundary [13, 14]. Since the plasmon is featured by the strongly localized evanescent wave, it can be considered as the extremely effective lens, which focuses the light beyond the diffraction limit [15-18]. Unique properties of plasmon have been extensively studied for Raman spectroscopy, plasmonic devices, and chemical transformation processes [1923]. Especially in the last case, the activation by plasmon energy has a great potential for overcoming many intrinsic limitations of conventional catalysts that made plasmon-driven catalysis one of the hottest topics [9, 24]. There is a range of outstanding examples, where plasmon was utilized for initiation of chemical reactions, including the oxidation of p-alkyl thiophenols and alcohols [25], azo-coupling of amino groups [26, 27], dissociation of hydrogen [28-32] and many synthetic methods [25-41]. Nevertheless, for plasmon catalysis, the expansion of reaction scope will propel to the next level of applicability. In this work, we present the click chemistry reaction azide-alkyne cycloaddition (AAC) as a unique example of plasmonics possibilities in the field of organic chemistry. Since the introduction of the click chemistry concept by Sharpless and co-workers [4243], the click reactions found their utilization in many application areas [44-45]. Through the diversity of possible click chemistry transformations, azide-alkyne cycloaddition (AAC) reaction become a paragon of click chemistry [45-47]. Becoming a prime example of click chemistry, AAC demonstrates great usability for modification of biomolecules and natural products, polymer transformations, drug synthesis, and surface modification [45, 48-50]. Nowadays, several basic approaches for AAC activation can be distinguished: thermal activation; utilization of metals catalysts [42-45], strain-promoted AAC [46] and UV-induced catalysis [47, 48]. As a consequence of listed advantages and width of possible activation ways, they have found comprehensive applications in material science [46, 58, 59]. Taking into account the growing number of scientific articles regarding the use of click chemistry for materials science, there is a strong need in the art to 2 ACS Paragon Plus Environment

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design the novel alternative approaches, catalyzing AAC on the surface with robustness to the existing repertoire of reactions [60]. In this contribution, for the first time, we demonstrate a new approach to the plasmonic activation of AAC. In our experimental concept, the reaction was performed through the grafting of 4-ethynylphenyl groups to surface plasmon polariton supported gold grating and their activation by excited plasmonic waves. Proposed approach expands the reaction scope of plasmon-induced chemical transformation as well as introduces an alternative way for AAC activation.

Experimental Materials Acetic acid (reagent grade, ≥ 99 %), diethyl ether, deionized water, methanol (puriss, absolute, ≥ 99.8 % (GC)), 4-ethynylaniline (97 %), p-toluenesulfonic acid monohydrate (ACS reagent, ≥ 98.5 %), 4-azidoaniline hydrochloride (97 %), phenylacetylene (98 %) were purchased from SigmaAldrich and used without further purification. Solution of Su-8 was purchased from Microchem, Germany. Samples preparation Grating preparation. Su-8 films were spin-coated onto freshly cleaned glass substrates and patterned using the linearly polarized excimer laser irradiation according the [21]. The gold and silver (purity of 99.99 %, provided by Safina, Czech Republic) were deposited onto a patterned surface by vacuum sputtering, thickness approx. 25 nm for gold and 16 nm for silver. 4ethynylbenzenediazonium tosylate (ADT-C≡CH) and 4-azidobenzenediazonium tosylate (ADT-N3) were synthesized according to the slightly modified published procedure [61] (for detailed information see SI). The metals surfaces were spontaneously modified by soaking in 2 mM freshly prepared aqueous solution of ADT-C≡CH or ADT-N3 for 20 min [62]. After modification metal substrates were rinsed under sonication sequentially with water, methanol, and acetone for 10 min and dried in desiccator Plasmon-driven azide-alkyne cycloaddition - direct experiment: The plasmon-assisted AAC and the corresponding time-dependent SERS measurements were carried out on gold grating modified by ADT-C≡CH using portable ProRaman-L spectrometer (785 nm). Every time before starting the process, spectra of the modified gold surface was recorded. For the surface AAC between 4-azidobenzoic acid and ethynyl groups on the surface, a 5 ml of 1mM solution of 4azidobenzoic acid in methanol/water (v/v=1:1) containing was added to the gold grating surface. After the image of the selected modified gold grating was focused using a 40× microscope 3 ACS Paragon Plus Environment

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(immersed in solution) objective. The laser beam is switched on to start the coupling reaction. The SERS on-line measurements were performed in the solution using 785 nm excitation wavelength with the laser beam focused to a spot with 25 μm diameter. The laser power was set to be 6,7, 8, 10, 14 and 18 μW/μm2. The conversion of surface groups was determined by characteristic Raman peak, located at 2098 cm-1 for the gold gratings and 2006 cm-1 for the silver gratings. Temperature control experiments. Schematic representation of control experiments for estimation of plasmon-induced samples heating is presented in Fig. S1. The gold gratings grafted with -Ar-C≡CH was placed in the Petri dish, the ultrathin leaf-type thermocouple was placed on the sample surface and fixed using the conductive paste. The laser beam (780 nm) was focused on the sample surface close to the working edge of the thermocouple, and the temperature changes were monitored up to the reaching the saturable value (3 minutes of illumination was found to be enough for the achievement of stabilized temperature value). The experiments were performed in two arrangements: in the air or the water/methanol solution. In the last case, the measurement of water/methanol solution temperature was also performed independently using a second thermocouple (Thomas Traceable® Waterproof Type K Thermometer probe) placed in the solution at the 0.2 cm distance from the illuminated place. Direct experiment at increased temperature. For experiments under increased temperature (50°C - this temperature ten time exceed the maximal surface heating under the laser illumination see the manuscript text), the SERS measurements were performed with laser intensity 18 μW/μm2 using a hot plate. Experiments with the silver grating. Silver grating modified by ADT-C≡CH, were immersed in the solution of 1mM 4-azidobenzoic acid, and illuminated with 785 nm, under the same conditions, as was described above. Subsequent SERS control experiments, (with 532 nm excitation wavelength) were performed using Advantage NIR Raman spectrometer (532 nm) on dry samples, after their removing from the reaction mixture and rinsing with water/methanol mixture in order to detect the possible trace concentrations of triazole moieties. Influence of surface groups on AAC. For this experiment gold gratings modified by ADTN3 were used. For the AAC between phenylacetylene and azide groups on the surface, a 10 ml of a 1mM solution of phenylacetylene in methanol/water (1:1) was added to the gold grating. All other conditions are the same as described before. Control of by-product formation 4-(4-phenyl-1H-1,2,3-triazole-1-yl)benzoic acid (1) was prepared according to [63]. 10-8 M water/methanol solution of 1 was drop deposited on the pristine gold grating, and Raman scattering was measured on ProRaman-L spectrometer (785 nm excitation wavelengths, laser power 15 mW). For the GC-MS analysis of reaction mixture after plasmon4 ACS Paragon Plus Environment

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induced AAC, a solution of 4-azidobenzoic acid were collected after continuous illumination with 785 nm laser (18 μW/μm2) for 40 s and analysed by GC-MS. The identification of dehydrogenation products was unequivocally established by a GC-MS ISQ TRACE™ 1300 (Thermo) with TRACE™ TR-5 GC Column. For GC-MS analyses, the column was coupled to a VG 70SE dual sector high-resolution mass spectrometer. Measurements technique The surface chemical composition was determined by X-ray photoelectron spectroscopy (XPS) using an Omicron Nanotechnology ESCAProbeP spectrometer fitted with monochromated Al K Alpha X-ray source (h= 1486.6 eV, spot size = 2x3 mm2). Binding energy positions were calibrated against Au4d7/2 peak set at 84.0 eV. For characterization of the sample surface and nanomechanical mapping the peak force AFM technique was applied using the Icon (Brucker) microscope. UV-Vis spectra were measured using Spectrometer Lambda 25 (Perkin-Elmer) in 3001000 nm wavelength range. Concentration of metals in all solutions was measured by atomic adsorption spectroscopy on AGILENT 280 FS AA spectrometer.

Results and Discussion For the detailed evaluation of plasmon-induced AAC, we utilized SPP supporting gold gratings with parameters, able to effectively support the excitation and propagation of plasmon waves [21, 23]. Schematic representation of a proposed experimental concept is given in Fig. 1. We started from the creation of periodical gold grating surface which provides efficient excitation of SPP waves and a huge concentration of electro-magnetic field near the noble metal surface. The gold grating surface was grafted with 4-ethynylbenzenediazonium tosylate (ADT-C≡CH) [62] and then immersed in the solution of 4-azidobenzoic acid for post-cycloaddition click reaction triggered through the SPP excitation. The Au surface grafting with -C6H4-C≡CH was confirmed by XPS and Raman (results are presented in the Tab. S1 and Fig. S2, S3). Apparent increase of carbon-related peak C(1s) at 284.7293 eV and the growth of C(1s)/Au(4f) intensity ratio owing to the aryl layer indicate the successful attachment of organic functional groups. The appearance of specific Raman bands, characteristic for aromatic acetylenes (2098 cm-1 C≡C str) and aromatic azides (2006 cm-1 azide antisym str) (see Tab. S2, Fig. S3) additionally confirm the gold surface grafting. The XPS results were also used for the calculation of the density of the grafted organic functional groups on the noble metal surface, which was found to be 6.22 molecule/nm2 (detailed description is given in the SI). The presence of carbon on the pristine grating surface can be attributed to a contribution from underlying polymer 5 ACS Paragon Plus Environment

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film and slight samples contamination during the sputtering procedure or carbon sorption from the air. The gold grating parameters were evaluated using AFM technique (Fig. 2A). It is evident that the created structure represents the well-ordered sinusoidal pattern with amplitude ca 55 nm and periodicity 280 nm. As was demonstrated in our previous works [23] such periodical structure can efficiently support the SPP excitation and propagation. Utilization of SPP for plasmon-driven catalysis, in turn, prolongs the lifetime of hot electrons, which contributes to better process efficiency, through the compensation of mismatch between the hot-electron relaxation time and the time of chemical transformation elementary act. The ability of gold gratings to support the SPP was confirmed by the UV-Vis spectroscopy (Fig. S4). The wavelength position of SPP was found to be near the 785 nm and therefore this wavelength was applied for the plasmon-induced AAC on the gold grating surface. In the next step we applied the laser irradiation for the SPP-based initiation of AAC on the gold grating surface through the illumination of samples, immersed in freshly-prepared solution of 4-azidobenzoic acid. It must be noted that the plasmon evanescent wave decreases exponentially in the surrounding dielectric environment and thus, the surface-grafted 4-ethynylphenyl groups were dominantly activated by SPP. We carried out in-situ SERS surveying of plasmon-catalyzed AAC induced by different laser power densities (Fig. 3, Fig. S5). As is evident from the Fig. 3 the Raman spectra of 4-ethynylphenyl and appropriate triazole functional groups are featured by the different peaks, of which changes were further applied for the kinetics investigation of AAC. For all laser power densities Raman peak intensities attributed to C≡C bond gradually decreased, when the new peak, attributed to triazole ring and –COOH groups (Tab. S2) appeared and gradually increased according to the conversion of starting materials to the reaction product. In-situ SERS monitoring over different laser powers demonstrated the strong dependence of reaction rate on the laser power density - the time required for the complete reaction was found to be strongly influenced by the laser intensities (Fig 3). In must be noted that for all applied laser power densities we observed full conversion and when the reaction is induced by the highest laser power density (18 μW/μm2), the full conversion was achieved almost immediately (40 s). However, when the less laser power density was applied, the time required for 100 % conversion (according to absolute disappearing of C≡C adsorption band) increases. For better “visibility” we present the SERS peak intensity of 2098 cm-1 peak, attributed to C≡C bond and SERS peak at 2098 cm-1, characteristic for triazole ring in the Fig. 4A as a function of reaction time. As is evident, the 2098 cm-1 Raman peak decreased gradually up to zero value, while the 2203 cm-1 peak simultaneously increased up to a constant value. The full conversion of surface groups takes place after the 40 s for 18 μW/μm2, 220 s for 14 μW/μm2, 390 s for 10 6 ACS Paragon Plus Environment

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μW/μm2, and 470 s for 8 μW/μm2 laser power densities. As the highest power density 18 μW/μm2 enable to perform plasmon-induced AAC in just 40 s, this laser power was used in the subsequent experiments. We also calculated the kinetic rate constants for all laser power densities (Fig. 4B) using equation: ln(Ct/C0) = ln(I2098(t)/I2098(0)) = kt+b, where I2098 is intensity of the Raman peak, indicating disappearance of phenylacetylene groups ring according to [64]. From Fig. 4 is evident that the formation of triazole ring starts immediately when laser illumination begins. With the increase of laser power density the rate constants dramatically raise; for instance, with the increase of laser power from 8 to 18 μW/μm2 – the reaction constant grew by one order of magnitude (Fig. 4). The formation of triazole on the surface was additionally proved by XPS (Fig. S2C). XPS survey spectrum after AAC demonstrates a decrease of Au (83.6 eV) peak and an increase of triazole attributed carbon peak C(1s) (285.6-293 eV). Moreover, the cycloaddition led to the formation of the new carbon-related peak (Fig. S2C - insert) observed at 287.2 eV (C(1s)), indicative for nitrogen-carbon bond (C–N). Additional nitrogen signal can also be used as a marker for the successful plasmon-induced AAC, since there was no elemental nitrogen present on the 4ethynyl grafted surface. The N(1s) spectra (Fig. S2C - insert) showed two peaks centered at 400.6 and 402.9 eV with a ratio of around 2:1 [65], indicating the presence of nitrogen atoms consistent with the formation of a triazole moiety. So, XPS results strongly proved the formation of triazole on the gold grating surface. In the next step, we intended to exclude the possible side effects and establish the plasmonic nature of AAC activation. One of the most discussed questions, in the field of plasmon-driven catalysis, is whether the reaction is undergoing under the plasmon or whether there are additional effects associated with impurities [19], heating [20], or photon (not plasmon) initiation [21]. For an additional check of metal trace amounts, we analyzed the solutions of diazonium salts and 4azidobenzoic acid using Atomic Adsorption Spectroscopy (AAS) revealing the absence of metal impurities. For the evaluation of potential plasmonic heating effects, we measured the surface temperature with thermocouple probes in the place of laser illumination and reaction medium after 3 minutes of irradiation — results presented in Fig. S6, indicating that the temperature increase does not exceed the 4oC even under the illumination with the highest available laser intensity (18 μW/μm2) when the experiments were performed in the water/methanol solution. Additionally, the simultaneous measurement of the water/methanol solution temperature does not indicate any changes of temperature during the illumination. It must be noted that the observed increase in surface temperature is insufficient for the AAC reaction since the azide-alkyne Huisgen cycloaddition requires keeping of reaction mixture under 100 °C for a few hours [66]. In order to 7 ACS Paragon Plus Environment

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experimentally differentiate heating, we investigated the influence of increased temperature on the plasmon induced AAC. Taking into account the measured value of surface heating under the illumination (4oC under 18 μW/μm2) we compared the reaction rates at the room and 50°C temperatures as the time-dependent intensities of 2203 and 2098 cm-1 bands (Fig. 5). It is evident that the temperature does not significantly affect the reaction rate - the reaction constants were found to be k50°C = -0.2104 s-1 and kRT = -0.2034 s-1 for 500C and RT respectively. As the difference between reactions constants is negligible, one may conclude that the temperature effects associated with plasmon-heating are negligible. We also evaluate the effect of light illumination (i.e. traditional photochemistry effect). Towards this end, the two types of grating were used: silver and gold gratings. Both gratings support the SPP excitation and propagation, however under the illumination with different wavelengths. Results of UV-Vis spectroscopy (Fig. 6) show that the SPP attributed absorption peak in the case of the silver grating is located near 530 nm, as opposed to the gold gratings (785 nm). Thus, illumination with 785 nm cannot excite any SPP wave in the case of the silver grating. In the next step the silver grating surface was modified by ADT-C≡CH (Fig. S2B), immersed in the solution of 4-azidobenzoic acids and illuminated with 785 nm (to avoid any possible mistakes, the control SERS measurements on the silver grating was performed with 532 nm, after the samples illumination with 785 nm, washing and drying). As in previous cases, the reaction was controlled by increasing the peak intensity at 2203 cm-1. It is evident (Fig. S3), that on the silver grating, under the illumination with 785 nm, which do not support the SPP excitation, the peak at 2203 cm-1 was not detected, indicating the absence of AAC reaction. Moreover, significant increase of the illumination time also does not lead to the appearance of 2203 cm-1 Raman band, confirming the key role of SPP in the AAC initiation. The control experiments also included the initiation of AAC using the illumination of grafted gold grating with 450 nm (this wavelength is far away from the plasmon excitation wavelengths range). The further SERS measurements (performed after the samples washing and drying) also indicate that no chemical transformation takes place additionally confirming the plasmonic nature of AAC initiation (Fig. S7). The potential formation of reaction by-product was proved using the reversal procedures, confirming that there were no additional by-products on the surface and in the reaction solution. For this purpose, we prepared the target triazole and drop-deposited it on the unmodified gold grating. The comparison of triazole SERS with our plasmon-induced results is given in Fig. S8 and the characteristic Raman bands (2200, 1570, 1390, 1330, 1107, 1077, 1024, 856, 720, 631 and 513 cm1)

measured in both cases are located at the same position. So, we did not observe any additional

peaks in the SERS spectra after plasmon induced AAC, indicating that no by-products are formed 8 ACS Paragon Plus Environment

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on the gold surface. The similar situation was observed in the case of MS analysis of reaction mixture (results are presented in the Fig. S9). In this case, no difference between the initial 4aziodibnzoic acid solution and residual solution after performing of plasmon-induced AAC reaction was found. So, we can conclude that no by-products are formed during the reaction since no trace amounts of additional compounds was detected. The plausible mechanism of the plasmon-induced reaction is presented in Fig. S10. According to the recent theories of plasmon-based chemical transformation initiation, the interaction of organic molecules with plasmon will lead to injection of hot electrons from plasmonic surface to organic species, and/or electron transition from LUMO to HOMO molecular orbitals, and/or to electric field induced stretching of chemical bonds. All of the above-mentioned mechanisms can potentially participate on the observed AAC initiation, including the injection of electron density, intramolecular electron transition or strong plasmon-related electric field activation of grafted chemical moieties. We also compared the present approach for plasmon-based initiation of AAC with another, commonly used or recently proposed methods. The comparative analysis of AAC initiation pathway presented in Tab. S3 with especially focuses on the advantages and limitation of each method. As is evident the plasmon-based initiation of AAC possess a range of additional advantages such as low increase of temperature during the reaction, possibility to avoid the utilization of toxic reagents and short reaction time. In the next step, the reactivity of 4-azidophenyl groups under plasmon activation was investigated. The gold grating surface was grafted by 4-azidobenzenediazonium tosylate using the same procedure as in the case of 4-ethynylphenyl groups (the density of grafted OFGs, calculated from the attenuation of gold-related XPS peak was found to be 14.5 molecules/nm2, indicating the formation of multimolecular layer structure - see SI). Plasmon-induced chemical transformation mechanism(s) occurs under the injection of hot electrons and/or plasmon-induced polarization of chemical bond. Both events suppose the close proximity of molecule, which should be activated, to the plasmonic surface. Thus, even grafted 4-azidophenyl will be dominantly activated by SPP under illumination. However, the common mechanism of AAC, presumes activation of acetylene group, no azide. Thus, plasmon induced reaction of grafted azidophenyl groups with dissolved phenylacetylene is expected to be limited (we further use the term “improper” initiation for this case). Indeed, these limitations can be partially transcended due to plasmon-activation of diffused phenylacetylene molecules from solution to the gold surface. The successful grafting of 4-azidophenyl groups was confirmed by XPS and SERS (Fig. S2, Tab. S1, Tab. S2). The narrow XPS spectra of N1 s demonstrate peak, where components are assigned to N―H/N―C(399.8 eV),N-/N―C (~401.2 eV) and N+(~404.05 eV), respectively 9 ACS Paragon Plus Environment

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according to [67]. The modified gratings were irradiated by a laser beam in the solution of phenylacetylene and the Fig. 3A shows the SERS spectra measured after the illumination with 18 μW/μm2 laser power for 40 s, i.e., the time required for full conversion in the case of “proper” initiation (for 4-ethynylphenyl grafted surface). It is evident that illumination for 40 s almost did not affect the original SERS spectrum. An increase in the illumination time by several times led to a partial appearance of characteristic triazole-related peaks and a corresponding decrease of azidophenyl-related Raman peaks. Observed changes in SERS spectra, however, are significantly less pronounced than in the case of “proper” initiation. Moreover, the reaction is saturated before the full conversion of phenyl organic moieties (the conversion of functional groups in the case of improper initiation does not exceed 52 %), which phenomenon can be attributed to the steric hindering due to the formation of the multilayer structure of phenyl azide (see. Fig. S11). Comparative reaction kinetics is presented in the Fig. 7. As is evident, the “proper” reaction initiation leads to a reaction with the much higher rate. Calculation of reaction kinetic, performed according to the [52], allows estimating the reaction constants (K) for both cases of initiation: “proper” initiation K=-0.2034 s-1; “improper” initiation K=-0.023 s-1. Comparison of these constants shows that the reaction rate decreased by a factor of 10, indicating the great influence of exactly 4-ethynylphenyl functional group plasmonic activation.

Conclusion In conclusion, we developed a new approach for the AAC reaction activation, based on the surface plasmon-polariton triggering. In particular, proposed initiation approach allows transformation of the grafted ethynyl moieties to the appropriate triazoles with high efficiency, in the absence of metal catalysts. We found that the reaction rate strongly depends on the laser power density. It was also demonstrated that the initiation of 4-ethynylphenyl groups dominantly promoted the reaction, while the application of plasmon activation of previously grafted 4-azidophenyl groups led to significantly decreased reaction rate. Additional series of control experiments, including the potential metal impurities, heating effect or diversity of plasmon absorption band and excitation wavelength was performed and convincingly demonstrate that the reaction is exactly activated by surface plasmon polariton wave. We believe that the suggested approach enables to widen the modern tool-box for plasmonic implementation in the field of chemical transformation.


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Acknowledgment This work was supported by the GACR under the project P108/12/G108, Tomsk Polytechnic University (VIU-RSCABS-196/2018), and European Structural and Investment Funds, OP RDE, funded project 'CHEMFELLS4UCTP' (No. CZ.02.2.69/0.0/0.0/17_050/0008485)

References [1] Chemical History: Reviews of the Recent Literature (Russell, Colin A., Roberts, Gerrylynn K., ed.s) Jeffrey Kovac, J. Chem. Ed. 2006. 83 (8), 1139. [2] M. Yan, Yu. Kawamata, Ph. S. Baran, Synthetic organic electrochemical methods since 2000: on the verge of a renaissance. Chem. Rev. 2017, 117, 13230–13319. [3] X. Lang, X. Chen, J. Zhao, Heterogeneous visible light photocatalysis for selective organic transformations. Chem. Soc. Rev. 2014, 43, 473-486. [4] R. A. Sheldon, Metrics of Green Chemistry and Sustainability: Past, Present, and Future. ACS Sus. Chem. Eng. 2018, 6, 32-48. [5] I. V. Kuchurov, M. N. Zharkov, L. L. Fershtat, N. N. Makhova, S. G. Zlotin, Prospective symbiosis of green chemistry and energetic materials. ChemSusChem 2017, 10, 3914-3946. [6] M. Yan, Y. Kawamata, P.S. Baran, Synthetic organic electrochemistry: calling all engineers. Angew. Chem. Int. Ed. 2018, 57, 4149-4155. [7] E. J. Horn, B. R. Rosen, Ph. S. Baran., Synthetic Organic Electrochemistry: An Enabling and Innately Sustainable Method. ACS Cent. Sci., 2016, 2, 302–308. [8] K. Kim, K. L. Kim, D. Shin, J.-D. Choi, Surface-enhanced Raman scattering of 4aminobenzenethiol on Ag and Au: pH dependence of b 2-type bands.J. Phys. Chem. C 2012, 116, 4774–4779. [9] Y. Zhang, Sh. He, W. Guo, Y. Hu, J. Huang, J. R. Mulcahy, W. D. Wei, Surface-plasmondriven hot electron photochemistry. Chem. Rev., 2018, 118, 2927–2954. [10] C. Clavero, Plasmon-induced hot-electron generation at nanoparticle/metal-oxide interfaces for photovoltaic and photocatalytic devices. Nat. Photonics 2014, 8, 95-103. [11] M. T. Sun, H. Xu, A novel application of plasmonics: plasmon‐driven surface‐catalyzed reactions. Small 2012, 8, 2777−2786. [12] M. D. Xiao, R. B. Jiang, F. Wang, C. H. Fang, J. F. Wang, J. C. Yu, Plasmon-enhanced chemical reactions. J. Mater. Chem. A 2013, 1, 5790−5805. [13] W. L. Barnes, A. Dereux, T. W. Ebbesen, Surface plasmon subwavelength optics. Nature 2003, 424, 824−830. 11 ACS Paragon Plus Environment

Langmuir 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 12 of 23

[14] J. Svanda, Y. Kalachyova, P. Slepicka, V. Svorcik, O. Lyutakov, Smart component for switching of plasmon resonance by external electric field. ACS Appl. Mater. Interfaces 2015, 8, 225-231. [15] M. L. Brongersma, N. J. Halas, P. Nordlander, Plasmon-induced hot carrier science and technology. Nat. Nanotechnol. 2015, 10, 25-34. [16] M. J. Kale, T. Avanesian, P. Christopher, Direct Photocatalysis by Plasmonic Nanostructures. ACS Catalysis 2014, 4, 116-128. [17] A. Manjavacas, J. G. Liu, V. Kulkarni, P. Nordlander, Plasmon-induced hot carriers in metallic nanoparticles. ACS Nano 2014, 8, 7630-7638. [18] A. J. Haes, R. P. Van Duyne, A unified view of propagating and localized surface plasmon resonance biosensors. Anal. Bioanal. Chem. 2004, 379, 920−930. [19] E. Plum, X. X. Liu, V. A. Fedotov, Y. Chen, D. P. Tsai, N. I. Zheludev, Metamaterials: optical activity without chirality. Phys. Rev. Lett. 2009, 102, 113902. [20] W. T. Chen, P. C. Wu, C. J. Chen, C.-J. Weng, H.-C. Lee, T.-J. Yen, C.-H. Kuan, M. Mansuripur, D. P. Tsai, Manipulation of multidimensional plasmonic spectra for information storage. Appl. Phys. Lett. 2011, 98, 171106 [21] Y. Kalachyova, D. Mares, V. Jerabek, P. Ulbrich, L. Lapcak, V. Svorcik, O. Lyutakov, Ultrasensitive and reproducible SERS platform of coupled Ag grating with multibranched Au nanoparticles. Phys. Chem. Chem. Phys. 2017, 19, 14761-14769. [22] R. Elashnikov, D. Mares, T. Podzimek, V. Švorčík, O. Lyutakov, Sandwiched gold/PNIPAm/gold microstructures for smart plasmonics application: towards the high detection limit and Raman quantitative measurements. Analyst, 2017, 142, 2974-2981. [23] O. Guselnikova, P. Postnikov, M. Erzina, Y. Kalachyova, V. Švorčík, O. Lyutakov, Pretreatment-free selective and reproducible SERS-based detection of heavy metal ions on DTPA functionalized plasmonic platform. Sens. Act. B 2017, 253, 830-838. [24] A. V. Zayats, S. Maier, Hot‐Electron Effects in Plasmonics and Plasmonic Materials. Adv. Opt. Mater. 2017, 5 1700508. [25] K. Akai, M. Futamata, Gap mode induced photocatalytic oxidation of p-alkyl thiophenol molecules on silver films. Chem. Phys. Lett. 2017, 675, 63-68. [26] Q. Ding, M. Chen, Y. Fang, Zh. Zhang, M. Sun, Plasmon-Driven Diazo Coupling Reactions of p-Nitroaniline via− NH2 or− NO2 in Atmosphere Environment. J. Phys. Chem. C 2017, 121, 5225– 5231. [27] Z. Zhang, D. Kinzel, V. Deckert, Photo-induced or plasmon-induced reaction: investigation of the light-induced azo-coupling of amino groups. J. Phys. Chem. C 2016, 120, 20978-20983. 12 ACS Paragon Plus Environment

Page 13 of 23 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Langmuir

[28] S. Mukherjee, F. Libisch, N. Large, O. Neumann, L. V. Brown, J. Cheng, J. B. Lassiter, E. A. Carter, P. Nordlander, N. J. Halas, Hot electrons do the impossible: plasmon-induced dissociation of H2 on Au. Nano Lett. 2013, 13, 240−247. [29] S. Mukherjee, L. A. Zhou, A. M. Goodman, N. Large, C. Ayala-Orozco, Y. Zhang, P. Nordlander, N. J. Halas, Hot-electron-induced dissociation of H2 on gold nanoparticles supported on SiO2. J. Am. Chem. Soc. 2014, 136, 64−67. [30] M. J. Landry, A. Gelle, B. Y. Meng, C. J. Barrett, A. Moores, Surface-Plasmon-Mediated Hydrogenation of Carbonyls Catalyzed by Silver Nanocubes under Visible Light. ACS Catal. 2017, 7, 6128–6133. [31] H. Huan, L. Zhang, Zh. Lv, R. Long, Ch. Zhang, Y. Lin, K. Wei, Ch. Wang, L. Chen, Zh.-Y. Li, Q. Zhang, Y. Luo, Y. Xiong, Unraveling surface plasmon decay in core–shell nanostructures toward broadband light-driven catalytic organic synthesis. J. Am. Chem. Soc. 2016, 138, 6822– 6828. [32] Zh. Yin, Y. Wang, Ch. Song, L. Zheng, N. Ma, X. Liu, S. Li, L. Lin, M. Li, Y. Xu, W. Li, G. Hu, Zh. Fang, D. Ma, Hybrid Au–Ag nanostructures for enhanced plasmon-driven catalytic selective hydrogenation through visible light irradiation and surface-enhanced Raman scattering. J. Am. Chem. Soc. 2018, 140, 864–867. [33] Z. L. Zhang, T. Deckert-Gaudig, T. Deckert, Label-free monitoring of plasmonic catalysis on the nanoscale. Analyst 2015, 140, 4325−4335. [34] D. B. Ingram, S. Linic, Water splitting on composite plasmonic-metal/semiconductor photoelectrodes: evidence for selective plasmon-induced formation of charge carriers near the semiconductor surface. J. Am. Chem. Soc. 2011, 133, 5202−5205. [35] M. Murdoch, G. I. N. Waterhouse, M. A. Nadeem, J. B. Metson, M. A. Keane, R. F. Howe, J. Llorca, H. Idriss, The effect of gold loading and particle size on photocatalytic hydrogen production from ethanol over Au/TiO 2 nanoparticles. Nat. Chem. 2011, 3, 489−492. [36] F. Wang, Ch. Li, H. Chen, R. Jiang, L.-D. Sun, Q. Li, J. Wang, J. C. Yu, Ch.-H. Yan, Plasmonic harvesting of light energy for Suzuki coupling reactions. J. Am. Chem. Soc. 2013, 135, 5588−5601. [37] N. Nguyen, A. Lamouri, Ch. Salameh, G. Lévi, J. Grand, L. Boubekeur-Lecaque, C. Mangeney, N. Félidj, Plasmon-mediated chemical surface functionalization at the nanoscale. Nanoscale, 2016, 8, 8633-8640. [38] I. Goykhman, B. Desiatov, J. Khurgin, J. Shappir, U. Levy, Locally oxidized silicon surfaceplasmon Schottky detector for telecom regime. Nano Lett. 2011, 11, 2219−2224.


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Page 14 of 23

[39] Z. Fang, Y. Wang, Z. Liu, A. Schlather, P. M. Ajayan, F. H. L. Koppens, P. Nordlander, N. J. Halas, Plasmon-induced doping of graphene. ACS Nano 2012, 6, 10222−10228. [40] H. Wenbo, St. K. Cronin, A Review of Surface Plasmon Resonance-Enhanced Photocatalysis. Adv. Fun. Mater. 2013, 23, 1612-1619. [41] X. Chen, H. Zhu, J. Zhao, Z. Zheng, X. Gao, Visible-light-driven oxidation of organic contaminants in air with gold nanoparticle catalysts on oxide supports. Angew. Chem. Int. Edn Engl. 2008, 47, 5353-5356. [42] H. C. Kolb, M. G. Finn, K. B. Sharpless, Click chemistry: diverse chemical function from a few good reactions. Angew. Chem. 2001, 113, 2056-2075. [43] H. C. Kolb, M. G. Finn, K. B. Sharpless, Click chemistry: Diverse chemical function from a few good reactions. Ang. Chem. Intern. Ed. 2001, 40 (11), 2004-2021. [44] X. Meng, K.J. Edgar, “Click” reactions in polysaccharide modification. Prog. Polym. Sci. 2016, 53, 52-85. [45] M. Meldal, Ch. W. Torno, Cu-catalyzed azide− alkyne cycloaddition. Chem. Rev. 2008, 108, 2952–3015. [46] J. E. Hein, J. C. Tripp, L. B. Krasnova, K. B. Sharpless, V. V. Fokin, Copper (I)‐catalyzed cycloaddition of organic azides and 1‐iodoalkynes. Angew. Chem., Int. Ed., 2009, 48, 8018-8021. [47] B. T. Worrell, J. A. Malik, V. V. Fokin, Direct evidence of a dinuclear copper intermediate in Cu (I)-catalyzed azide-alkyne cycloadditions. Science, 2013, 340, 457-460. [48] J. C. Jewett, C. R. Bertozzi, Cu-free click cycloaddition reactions in chemical biology. Chem. Soc. Rev. 2010, 39, 4, 1272-1279. [49] P. Thirumurugan, D. Matosiuk, K. Jozwiak, Click chemistry for drug development and diverse chemical–biology applications. Chem. Rev. 2013, 113, 7, 4905-4979. [50] A. Qin, J. W. Y. Lam, B. Z. Tang, Click polymerization. Chem. Soc. Rev. 2010, 39, 7, 25222544. [51] P. N. Liu, J. Li, F. H. Su, K. D. Ju, L. Zhang, C. Shi, H. H. Y. Sung, I. D. Williams, V. V. Fokin, Z. Lin, G. Jia, Selective formation of 1, 4-disubstituted triazoles from ruthenium-catalyzed cycloaddition of terminal alkynes and organic azides: scope and reaction mechanism. Organometallics, 2012, 31, 4904-4915. [52] B. T. Worrell, J. A. Malik, V. V. Fokin, Direct Evidence of a Dinuclear Copper Intermediate in Cu(I)-Catalyzed Azide-Alkyne Cycloadditions. Science 2013, 457-460. [53] M. A. Morozova, M. S. Yusubov, B. Kratochvil, V. Eigner, A. Bondarev, A. Yoshimura, A. Saito, V. V. Zhdankin, M. E. Trusova, P. S. Postnikov, Regioselective Zn (OAc) 2-catalyzed azide– alkyne cycloaddition in water: the green click-chemistry. Org. Chem. Front. 2017, 4, 978-985. 14 ACS Paragon Plus Environment

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Langmuir

[54] C. Wang, D. Ikhlef, S. Kahlal, J.-Y. Saillard, D. Astruc, Metal-catalyzed azide-alkyne “click” reactions: Mechanistic overview and recent trends. Coord. Chem. Rev., 2016, 316, 1-20. [55] N. J. Agard, J. A. Prescher, C. R. Bertozzi, A strain-promoted [3+ 2] azide− alkyne cycloaddition for covalent modification of biomolecules in living systems. J. Am. Chem. Soc. 2004, 126, 15046-15047. [56] M. A. Tasdelen, Y. Yagci, Light‐induced click reactions. Angew. Chem. Int. Ed. 2013, 52, 5930–5938. [57] O. Yetiskin, S. Dadashi-Silab, Sh. Bahadar, A. Mohamed, Y. Yagci, Visible‐Light‐Induced Copper (I)‐Catalyzed Azide‐Alkyne Cycloaddition Initiated by Zinc Oxide Semiconductor Nanoparticles. Asian J. Org. Chem. 2015, 4, 442-444. [58] S.Yoshida, J. Tanaka, Y. Nishiyama, Y. Hazama, T. Matsushita, T. Hosoya, Further enhancement of the clickability of doubly sterically-hindered aryl azides by para-amino substitution. Chem. Comm. 2018, 54, 13499-13502. [59] C. P. Ramil, Q. Lin, Photoclick chemistry: a fluorogenic light-triggered in vivo ligation reaction. Curr. Opin. Chem. Biol. 2014, 21, 89-95. [60] J. Escorihuela, A. T. Marcelis, H. Zuilhof, Metal‐Free Click Chemistry Reactions on Surfaces. Adv. Mater. Interfac., 2015, 2, 1500135. [61] K. V. Kutonova, M. E. Trusova, P. S. Postnikov, V. D. Filimonov, J. A. Parello, A simple and effective synthesis of aryl azides via arenediazonium tosylates. Synthesis 2013, 45, 2706-2710. [62] O. Guselnikova, P. Postnikov, R. Elashnikov, M. Trusova, Y. Kalachyova, M. Libansky, J. Barek, Z. Kolska, V. Svorcik, O. Lyutakov, Surface modification of Au and Ag plasmonic thin films via diazonium chemistry: Evaluation of structure and properties. Colloids Surf. A 2017, 516, 274-285. [63] F. Himo, T. Lovell, R. Hilgraf, V. V. Rostovtsev, L. Noodleman, K. B. Sharpless, V. V. Fokin, Copper (I)-catalyzed synthesis of azoles. DFT study predicts unprecedented reactivity and intermediates. J. Am. Chem. Soc., 2005, 127(1), 210-216. [64] R. Liu, Z. He, J. Sun, J. Liu, G. Jiang, Tracking the Fate of Surface Plasmon Resonance‐Generated Hot Electrons by In Situ SERS Surveying of Catalyzed Reaction. Small 2016, 12, 46, 6378–6387. [65] A. Bensghaïer, Z. Salmi, B. Le Droumaguet, A. Mekki, A. A. Mohamed, M. Beji, M. M. Chehimi, Diazonium interface chemistry and click polymerization: A novel route for carbon nanotube‐polytriazole nanocomposites. Surf. Interface Anal. 2016, 48, 7, 509-513. [66] R. Huisgen, Kinetics and mechanism of 1, 3‐dipolar cycloadditions. Angew. Chem. Internat. Edit., 1963, 11, 633-645. 15 ACS Paragon Plus Environment

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[67] A. Saad, M. Abderrabba, M.M. Chehimi, X‐ray induced degradation of surface bound azido groups during XPS analysis. Surf. Interface Anal. 2017, 49, 4, 340-344.

Figure caption Fig. 1 Schematic illustration of the plasmon-assisted azide-alkyne cycloaddition on the gold grating surface. Fig. 2 AFM topography measured on gold grating grafted by ADT-C≡CH before (A) and after (B) plasmon assisted reaction with 4-azidobenzoic acid at laser power 8 μW/μm2 after 200 s. Fig. 3 Time-dependent SERS spectra of plasmon-assisted AAC under continuous exposure to a 785 nm laser intensities of 8 (A, B), 14 (C, D), and 18 μW/μm2 (E, F) on gold grating grafted by ADTC≡CH Fig. 4 (A) - the time-depended intensities of the disappearing (at 2203 cm-1, C-H stretching of C≡CH) and appearing (2098 cm-1, imidazole ring stretching) Raman bands for different laser powers (8, 10 14, and 18 μW/μm2); (B) – kinetic curves of plasmon-induced AAC for different laser powers (8, 10 14, and 18 μW/μm2) and reaction constants calculated according to the 1st order kinetic equation. Fig. 5 Time-dependent intensity of the disappearing (at 2203 cm-1, C-H stretching of -C≡CH) and appearing (2098 cm-1, imidazole ring stretching) under the plasmon triggering Raman bands measured at room temperature and at 50°C. Fig. 6 (A) – UV-Vis spectra of gold and silver grating; (B) - time-depended intensity of triazole-related peak appeared under the plasmon induced AAC (illumination with 785 nm wavelength, laser power 18 μW/μm2) measured on the gold and silver gratings surfaces. Fig. 7 (A) - Raman spectra of gold grating grafted by ADT-N3, after 40 and 380 s of plasmon-assisted reaction with phenylacetylene, laser power - 18 μW/μm2; (B) - kinetic curves (according to the 1st order kinetic equation) of plasmon-induced AAC for proper and improper reaction activation.


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Fig. 3


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Fig. 4


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Fig. 6


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Surface plasmon-polariton: a novel initiation way for azide alkyne

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