Steric hindrance and exchange in the coadsorption of octanethiol and decyl thiocyanate on Au(111)

Formation and Surface Structures of Highly Ordered Self-Assembled Monolayers of Alkyl Selenocyanates on Au(111) via Ambient-Pressure Vapor Deposition

“…This result implies that most CN species were readily removed from the surfaces during SAM formation by solution or vapor deposition (Figure S1 in the Supporting Information), which is consistent with earlier works. , As a result, the adsorption of OSC on Au(111) led to the formation of octaneselenolate SAMs (Figure S2 in the Supporting Information). This formation mechanism of SAMs by organic selenocyanates (R-SeCN) on the gold surface is quite similar to that by organic thiocyanates (R-SCN) with a sulfur headgroup, as demonstrated before. ,,− …”

“…Organic thiols are the best model compounds because they spontaneously form closely packed SAMs with a molecularly controllable thickness on gold surfaces via the formation of S–Au chemical bonds. ,,, SAMs of alkanethiols with a normal alkyl chain at saturation coverage on gold have particularly well-ordered domains with a hexagonally packed (√3 × √3)­R30° or c (4 × 2) structure. ,,,,, However, a drawback of using thiols for SAM preparation is that they can readily be oxidized to other oxidized species in the solution, resulting in undesirable structural defects and inhomogeneous interface structures in SAMs. , Therefore, new molecular assemblies on metals have been developed using S-containing alternatives having high chemical stability in solution or air such as organic thioacetates, ,− thiosulfates, thiocyanates, − and sulfenyl chlorides . Direct adsorption of organic thioacetates on gold in the solution led to the formation of less ordered SAMs, ,− , whereas more ordered SAMs could be prepared via in situ deprotection of acetyl groups using specific deprotection reagents. , Other alternatives on gold showed similar structural behaviors: they usually form SAMs with inferior structural quality compared to the analogue thiols, but the structural quality of these SAMs was enhanced significantly using optimized SAM preparation conditions. − …”

Self‐Assembled Monolayers of Alkanethioacetates on Au(111) in Ammonium Hydroxide Solution

“…1,2,19,24,25 However, one drawback to using thiols is that in solution they can readily transform by oxidation to disulfides or sulfonate during SAM formation. 8,[27][28][29] To minimize this undesirable side reaction, other precursors such as chemically stable thiocyanates [30][31][32][33][34][35] or acetylprotected thiols (thioacetate) 26,27,29,[36][37][38][39][40][41][42][43][44][45][46][47][48][49][50] have been developed for SAM preparation. Various acetyl-protected thiols in particular have often been used for the preparation of SAM-based electronic devices via in situ deprotection of acetyl groups.…”