Immobilization of Cryptophane Derivatives onto SiO₂/Au and Au Substrates

Abstract

The synthesis of a cryptophane molecule bearing five methoxy substituents and an alkanethiol chain, 4, as well as its subsequent grafting onto a gold surface, is reported. Immobilization of cryptophane derivatives onto silica (SiO2/Au) surfaces was also performed by reacting a cryptophane molecule bearing one or six acid functions, 5 or 6, respectively, with an amino-terminated self-assembled monolayer (SAM). Polarization modulation infrared reflection-absorption spectroscopy (PM-IRRAS) was used to characterize the two types of cryptophane monolayers. Surface coverage of cryptophane monolayers was estimated by comparing the PM-IRRAS intensity of cryptophane bands with that calculated from the optical constants of pentamethoxy-cryptophane for a compact monolayer. A very efficient grafting of 4 onto a gold surface was found, with a surface coverage close to 100%. On the other hand, the reaction of mono-acid, 5, or hexa-acid, 6, cryptophanes with amino-terminated SAM was less efficient, since the surface coverage did not exceed 15%. Finally, a good surface coverage (75%) was also obtained by using a cysteamine coupling agent to modify 5 before its grafting onto a gold surface.

Immobilization of Cryptophane Derivatives onto γ-Fe2O3 Core–Shell Magnetic Nanoparticles

“…The presence of a linker between the cryptophane molecule and the surface seems to be necessary to improve the immobilization of the cryptophane derivatives. Similar conclusions have been drawn for the immobilization of cryptophane derivatives onto flat surfaces …”

“…We have previously reported the immobilization of cryptophane derivatives onto silica (SiO 2 /Au) and gold flat surfaces . Three strategies were considered to immobilize cryptophane derivatives onto these surfaces.…”

“…23 We have previously reported the immobilization of cryptophane derivatives onto silica (SiO 2 /Au) and gold flat surfaces. 24 Three strategies were considered to immobilize cryptophane derivatives onto these surfaces. The first strategy involved the grafting of a cryptophane derivative (pentamethoxy-cryptophane) bearing an alkanethiol chain, 1, in one step, onto a gold surface.…”

“…The synthetic route used to obtain pentamethoxy-cryptophane bearing an alkanethiol chain, 1, has been previously reported. 24 A cryptophane derivative bearing an alkyl chain with a terminal iodine atom was first prepared by reacting for 48 h at 80 °C cryptophanol and 1,10-diiododecane (5 equiv), in the presence of an excess of cesium carbonate in a mixture of dry dichloromethane and acetone. The resulting compound was then allowed to react with potassium thio-acetate in acetone at 80 °C.…”

Influence of the grafting process on the orientation and the reactivity of azide-terminated monolayers onto silica surface

“…The optical constants (refractive index and extinction coefficient) of 4 have been determined in the infrared spectral range from polarized attenuated total reflectance (ATR) spectra using a known procedure (Supporting information, Figs. S2a and S2b) [52,53]. The linear dependence of the IRRAS intensity of the ν a CH 2 mode with the monolayer thickness (Supporting information, Fig.…”