Anchoring and packing of self-assembled monolayers ofsemithio-bambusurils on Au(111)

Abstract

Self-assembled monolayers have been formed of semithio-bambusurils that undergo conformational changes to direct all S atoms to the gold surface.

Selective Perchlorate Sensing Using Electrochemical Impedance Spectroscopy with Self‐Assembled Monolayers of semiaza‐Bambusurils

“…We also determined the fraction of sulfur anchoring groups that participated in binding to the metal surface for each analyzed SAM by summing the integrals of both bound and unbound S 2p bands. For example, in the XPS spectra of 4 a , the calculated value obtained for the bound sulfur was 61 % (Table 2), implying that sulfur atoms at both rims are involved in binding to the Au surface and suggesting less dense layers with potentially complete loss of anion binding affinity [34] . In contrast, a smaller fraction of bound S−Au was observed in the XPS spectra of SAMs of 4 c (36 %), inferring that only one rim is involved in the assembly process onto the gold surface.…”

“…For example, in the XPS spectra of 4 a, the calculated value obtained for the bound sulfur was 61 % (Table 2), implying that sulfur atoms at both rims are involved in binding to the Au surface and suggesting less dense layers with potentially complete loss of anion binding affinity. [34] In contrast, a smaller fraction of bound SÀ Au was observed in the XPS spectra of SAMs of 4 c (36 %), inferring that only one rim is involved in the assembly process onto the gold surface. The attenuation of the bound sulfur signal caused by the location of these atoms at the bottom of the SAM may explain the < 50 % value observed here.…”

“…A wide variety of selective receptors based on host-guest chemistry include cyclodextrins (CDs), [25][26][27] crown ethers, [28,29] calixarenes, [30,31] cucurbit[n]urils (CB[n]s), [32] pillarenes, [33] and bambus [6]urils (BU [6]s). [34] Although cation-detecting sensors based on SAMs have been developed, anion-detecting SAMs have remained challenging.…”

“…[45] An earlier study showed that anchoring semithio-BU[n] (n = 4, 6) to an Au surface forms self-assembled monolayers with strong interactions between the thiocarbonyl groups and the metal surface. [34] Unfortunately, while the electrochemical measurements proved that electron transfer occurred through the SAMs, and XPS confirmed that thiocarbonyl sulfur atoms were chemisorbed to the Au(111), forming ordered domains of SAMs, the molecules underwent large conformational changes that optimized their layer formation but reduced their anion binding.…”

Inherently Chiral Bambus[4]urils

“…These macrocycles are rigid molecules due to the high steric demands of their subunits, which are locked in an alternate arrangement. Moreover, we demonstrated that sulfur analogues of BU[4], which are too small to accommodate any type of guest, have shown much potential for the formation of metal–organic chain polymers , and in anchoring self-assembled monolayers (SAMs) on gold surfaces . Therefore, designing inherently chiral hetero -BUs would be appealing for developing applications in the field of chiral sensing technologies.…”