Supporting Information. Surface-Enhanced Polymerization via Schiff-base Coupling. at the Solid-Water Interface under ph-control. and Claudio Goletti d

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1 Supporting Information Surface-Enhanced Polymerization via Schiff-base Coupling at the Solid-Water Interface under ph-control Marco Di Giovannantonio, a,b Tomasz Kosmala, a,c Beatrice Bonanni, d Giulia Serrano, a Nicola Zema, b Stefano Turchini, b Daniele Catone, b Klaus Wandelt, c Dario Pasini, e Giorgio Contini, b,a,* and Claudio Goletti d a Physics Department, University of Rome Tor Vergata, Via della Ricerca Scientifica 1, I Roma, Italy b Istituto di Struttura della Materia, CNR, Via Fosso del Cavaliere 100, Roma, Italy c Institute of Physical and Theoretical Chemistry, University of Bonn, Wegelerstraße 12, D Bonn, Germany d Physics Department and CNISM, University of Rome Tor Vergata, Via della Ricerca Scientifica 1, I Roma, Italy e Department of Chemistry and INSTM Research Unit, University of Pavia, Viale Taramelli, 10, Pavia, Italy S1

2 Supporting Information: Contents 1. Hanging meniscus configuration adopted before XPS investigations 2. Comparison between the two different procedures adopted for preparation of I/Au(111) before XPS and STM measurements 3. XPS characterization of the adsorbed iodine 4. Additional evidence of the formation of π-conjugated polymers from O 1s XPS data 5. Air stability of the π-conjugated polymers 6. Not-normalized UV-Vis absorption spectra on aqueous solution containing ASB and TPA 7. FT-IR and UV-Vis absorption measurements on the precipitate obtained from aqueous solution containing ASB and TPA at ph greater than 4.0 S2

3 1. Hanging meniscus configuration adopted before XPS investigations Figure S1. (a) picture and (b) scheme of the hanging meniscus configuration adopted to prepare the I/Au(111) surface and to adsorb the organic molecules at the desired ph from the liquid phase before transfer in vacuum for XPS characterization. The black arrow in (b) indicates the rotation of the transfer bar to remove the surface from the solution and let the liquid run off. S3

4 2. Comparison between the two different procedures adopted for preparation of I/Au(111) before XPS and STM measurements Figure S2. The two different procedures adopted for preparation of I/Au(111) before STM and XPS experiments lead to surfaces with the same characteristics. (a, c) LEED patterns and (b, d) STM images of (a) bare Au(111) surface prepared in UHV by repeated sputtering and annealing cycles (E p =63eV); (b) bare Au(111) surface prepared under argon flux by flame annealing (74 74 nm 2, V b =-300 mv, I t =1 na, imaged in Ar atmosphere); (c) I/Au(111) surface prepared from the UHV cleaned gold (E p =57eV); (d) I/Au(111) surface prepared from the flame annealed Au(111) ( nm 2, V b =-33 mv, I t =1 na, imaged in 1 mm KI). (b) herringbone appearance typical for (22 3) reconstruction 1-2 is visible in STM image of the bare Au(111) surface prepared by flame annealing as well as (a) extra spots surrounding the primary spots of the hexagonal gold bulk surface are present in the LEED pattern of the bare Au(111) surface prepared in UHV. 1, 3 Iodine superstructure is visible in both (d) in situ STM image (the distance between the protrusions is 0.55±0.05 nm) and (c) ex situ LEED pattern (where the ( 3 3)R30 supercell is observed). S4

5 3. XPS characterization of the adsorbed iodine Figure S3. Synchrotron radiation I 3d 5/2 XPS spectra of a I/Au(111) surface after emersion from a solution containing ASB or ASB+TPA at the reported ph. The spectrum of the I/Au(111) surface (after emersion from the KI solution) is reported for comparison. 4. Additional evidence of the formation of π-conjugated polymers from O 1s XPS data Figure S4. Synchrotron radiation O 1s XPS spectra of a I/Au(111) surface after emersion from a solution containing ASB and TPA at ph 1.7 and 4.0 or ASB at ph 1.0 (red, blue and black curves, respectively). The baseline of each curve has been vertically shifted. The blue curve has BE S5

6 position (about ev) and intensity similar to the spectrum obtained without TPA (black curve), demonstrating that the oxygen observed at ph 4.0 is mainly related to contaminations adsorbed on the I/Au(111) surface (since oxygen is not present in ASB). The signal at ph 1.7 (red curve), instead, presents a chemical shift toward higher BE and increased intensity, witnessing that the component centered at about ev can be attributed to oxygen atoms in the aldehyde functionalities of intact TPA and in the intermediate state of the Schiff-base coupling (Scheme 1) (analogous BE shift has been observed when molecular oxygen is adsorbed on gold nanoparticles compared to oxygen adsorbed on carbon atoms of HOPG) Air stability of the π-conjugated polymers Figure S5. Air stability of the π-conjugated polymers. N 1s XPS spectrum for I/Au(111) emersed from a solution containing ASB and TPA at ph 4.0 (black curve). The as measured sample has been then brought out of the vacuum chamber, exposed to air for 30 minutes, transferred back in vacuum and measured again (red curve). No significant changes are observed in the spectrum, demonstrating the robustness of the polymeric layer in air. Data are presented after Shirley background subtraction. 5 S6

7 6. Not-normalized UV-Vis absorption spectra on aqueous solution containing ASB and TPA Figure S6. UV-Vis absorption spectra for ASB and TPA dissolved in aqueous solution at the ph indicated in the legend. 7. FT-IR and UV-Vis absorption measurements on the precipitate obtained from aqueous solution containing ASB and TPA at ph greater than 4.0 Figure S7. Analysis of the precipitate obtained from aqueous solution containing ASB and TPA at ph greater than 4.0. (a) FT-IR spectra of the powders of ASB and TPA are shown in red and blue, respectively, and are in agreement with those reported in databases for the isolated compounds. 6 Spectrum of the precipitate obtained in aqueous solution from ASB and TPA at ph 5 filtered and S7

8 dried is shown in black and presents the typical signal for imine bond between 1600 and 1625 cm FT-IR measurements show that the precipitate consist of π-conjugated polymers, final product of the Schiff-base coupling. (b) UV-Vis absorption spectrum for the precipitate obtained in aqueous solution from ASB and TPA at ph 5, filtered, dried and dissolved in CH 2 Cl 2 (black curve). Absorption spectra of ASB alone and TPA alone in aqueous solution at ph 1.0 are reported for comparison (red and blue curves, respectively). The spectrum of TPA does not change varying the ph. The absorption band at about 400 nm is characteristic of π-conjugated polymers formed by ASB and TPA according to the Schiff-base coupling. S8

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