Diazocine-functionalized TATA platforms

Abstract

Recently, it has been shown that the thermochemical cis→trans isomerization of azobenzenes is accelerated by a factor of more than 1000 by electronic coupling to a gold surface via a conjugated system with 11 bonds and a distance of 14 Å. The corresponding molecular architecture consists of a platform (triazatriangulenium (TATA)) which adsorbs on the gold surface, with an acetylene spacer standing upright, like a post in the middle of the platform and the azobenzene unit mounted on top. The rate acceleration is due to a very peculiar thermal singlet–triplet–singlet mechanism mediated by bulk gold. To investigate this mechanism further and to examine scope and limitation of the “spin-switch catalysis” we now prepared analogous diazocine systems. Diazocines, in contrast to azobenzenes, are stable in the cis-configuration. Upon irradiation with light of 405 nm the cis-configuration isomerizes to the trans-form, which slowly returns back to the stable cis-isomer. To investigate the thermal trans→cis isomerization as a function of the conjugation to the metal surface, we connected the acetylene spacer in meta (weak conjugation) and in para (strong conjugation) position. Both isomers form ordered monolayers on Au(111) surfaces.

Coverage‐Controlled Superstructures of C3‐Symmetric Molecules: Honeycomb versus Hexagonal Tiling

“…Furthermore, the TOTA platform and the related compound triazatriangulenium are very versatile and the methyl moiety may be exchanged for other moieties of interest. This has been demonstrated for small moieties such as hydrogen, ethyl, ethynyl, and propynyl as well as porphyrins, diazocine, norbornadiene, imine, and azobenzene derivatives …”

“…This has been demonstrated for small moieties such as hydrogen, ethyl, ethynyl, and propynyl [43][44][45] as well as porphyrins,diazocine,norbornadiene,imine,and azobenzene derivatives. [32,35,40,41,[46][47][48] Using low-temperature scanning tunneling microscopy (STM) along with density functional theory (DFT) calcula-Abstract: The competition between honeycomb and hexagonal tiling of molecular units can lead to large honeycomb superstructures on surfaces.Suchsuperstructures exhibit pores that may be used as 2D templates for functional guest molecules.H oneycomb superstructures of molecules that comprise aC 3 symmetric platform on Au(111) and Ag(111) surfaces are presented. The superstructures cover nearly mesoscopic areas with unit cells containing up to 3000 molecules,m ore than an order of magnitude larger than previously reported.…”

Substituted Dibenzodiazocines: Rapid Synthesis and Photochemical Properties

“…A particular focus was put onto molecules, which can be integrated into biochemical systems via suitable linker groups. In contrast to many previous publications, 16,19,27,28 we decided to use the hydroxyl group rather than the amino group, as we were planning to open a window into carbohydrate chemistry, where the typical functional groups are hydroxyl groups. Consequently, a number of protected OH groups, such as methoxymethoxy (OMOM) or benzyloxy (OBn), were tested together with other substituents, which are known to significantly alter the switching behavior in the acyclic azobenzene series.…”

Predicting a New Δ‐Proton Sponge‐Base of 4,12‐Dihydrogen‐4,8,12‐triazatriangulene through Proton Affinity, Aromatic Stabilization Energy, and Aromatic Magnetism

“…Triangulene, or is equally named Clar's hydrocarbon, is a six‐fused‐rings hexacyclic compound postulated by Clar [47–48] and synthesized by Pavliček and coworkers [49] . One of the triangulene derivatives is 4,8,12‐triazatriangulene (TATA), a compound of great importance in contemporary chemistry [50–56] …”