Direct growth of crystalline triazine-based graphdiyne using surface-assisted deprotection–polymerisation

Graphdiyne polymers have interesting electronic properties due to their π-conjugated structure and modular composition. Most of the known synthetic pathways for graphdiyne polymers yield amorphous solids because the irreversible formation of carbon–carbon bonds proceeds under kinetic control and because of defects introduced by the inherent chemical lability of terminal alkyne bonds in the monomers. Here, we present a one-pot surface-assisted deprotection/polymerisation protocol for the synthesis of crystalline graphdiynes over a copper surface starting with stable trimethylsilylated alkyne monomers. In comparison to conventional polymerisation protocols, our method yields large-area crystalline thin graphdiyne films and, at the same time, minimises detrimental effects on the monomers like oxidation or cyclotrimerisation side reactions typically associated with terminal alkynes. A detailed study of the reaction mechanism reveals that the deprotection and polymerisation of the monomer is promoted by Cu(ii) oxide/hydroxide species on the as-received copper surface. These findings pave the way for the scalable synthesis of crystalline graphdiyne-based materials as cohesive thin films.

were recorded in a suitable range centered around the emission maximum between 450 and 760 nm.
Solid-state Raman spectroscopy: Solid-state Raman spectra were recorded on a DXR Raman spectrometer (Thermo Scientific) interfaced with an Olympus microscope, employing a 20x objective. The 785 nm (diode-pumped solid-state laser) excitation lines were used. The laser power ranged from 0.1 to 1%. The full-scale grating was used for all measurements. The raw spectrum is reported due to the high fluorescence background.
X-ray photoelectron spectroscopy (XPS): XPS measurements were conducted using an Al Kα (1486.6 eV) source for excitation. The core level signals were fitted using Voigt peaks (Gaussian/Lorentzian) and a nonlinear Shirley-type background. The energy scale and binding energy of the spectrometer were calibrated with triazine species at the binding energies of the N 1s spectrum at 399.0 eV. For the XPS analysis of the Cu 2p region, The TzG on Copper was washed in a glove box to avoid surface oxidation, the sample manipulation for the measurements was also performed in a glove box environment. Further, the X-ray photoelectron spectroscopy (XPS) was performed in an ultrahigh vacuum chamber (base pressure 2x10 -9 mbar) using a JEOL JPS-9030 set-up comprising a hemispherical photoelectron spectrometer and a monochromatic Al Kα (hν = 1486.6 eV) X-ray source. The Cu 2p and Cu LMM spectra were acquired with an overall energy resolution of 0.9 eV and 1.25 eV, respectively, as determined on a polycrystalline Ag 3d core level. The spectra of TzG on copper were corrected for charging by shifting the C1s peaks to 284.6 eV BE, to match the C1s binding energy of adventitious carbon observed on the as-received copper foil.
Powder X-ray (PXRD): measurements were performed with a Bruker D8 Advance diffractometer using Bruker AXS D8 Advanced SWAX diffractometer with Cu Kα (λ = 0.15406 nm) as a radiation source. Samples were measured from 1 to 60° 2θ with the step of 0.0102° 2θ secondary graphite monochromator and LYNXEYE XE detector.

Scanning electron microscopy (SEM) and Energy-dispersive X-ray spectroscopy (EDX):
The sample morphology was investigated using a scanning electron microscope (SEM, GeminiSEM 500, Carl Zeiss GmbH, Germany) operating at 15kV. The samples were mounted on SEM stubs with adhesive carbon tape and imaged in plain view. Elemental mapping was carried out using the same SEM instrument equipped with an energy-dispersive X-ray spectrometer (EDX, XFlash 6130, Bruker GmbH, Germany) operating at 15kV.
Then the reaction vessel was charged with a copper foil (as received). The reaction vessel was then sealed tightly with a teflon cap and heated in an oven at 60 o C for 72 h. After the reaction, the copper foil was removed from the reaction mixture and washed with DMF, THF, CHCl3, deionized water, and MeOH. Then polymer-coated copper foil was submerged in an aqueous solution of H3PO4 (1M). Within seconds, the flakes delaminate from the copper substrate (see Supplementary video V1). The as-synthesized TzG were then subjected to a wash with HCl (1M) to remove excess copper, followed by washing with NH4OH solution (1M) to remove the trapped HCl salts. The films were then subjected to wash with THF, MeOH, DMF, and Acetone. Finally, the product was dried under vacuum for 24 h at 120 °C to yield yellow-orange films.

Energy-dispersive X-ray (EDX):
Fig. S15 Energy-dispersive X-ray (EDX) spectra and the ratio of elements detected by EDX in wt% of (a) TzG as synthesized on copper, and (b) TzG after washing and drying.

XPS analysis of as-received vs Argon sputtered Copper foil
Fig. S26 X-ray photoelectron spectroscopy (XPS) data for as-received copper foil (red) and Ar sputtered copper foil (black).

Fig. S26
Control experiments to verify active species for the formation of diacetylene bridge, reaction conditions: (1 mmol) of TMS-Acetylene, (3 mmol) of copper salts, 60 o C, 3 days; note: For the glove box experiments, copper salts were dried at 120 o C for 12 h, and anhydrous pyridine was degassed with argon for 1 h before use.