Trimesityltriangulene: a persistent derivative of Clar's hydrocarbon

Abstract

Triangulene, known as Clar’s hydrocarbon, is a prototypical non-Kekulé diradical comprised of six benzenoid rings fused in a triangular shape. We synthesized and characterized its trimesityl derivative, illustrating that three...

Nonacethrene Unchained: A Cascade to Chiral Contorted Conjugated Hydrocarbon with Two sp3-Defects

“…A similar dual reactivity has recently been observed for sigmarene . In the past, various aspects of reactivity of these and analogous systems were subject to extensive investigations. ,− In contrast, the current research is largely focused on the properties of extended diradicaloids, with efforts being made to suppress ,− their reactivity in order to obtain stable or persistent systems. A few recent reports indicate, however, that the reactivity of “unchained” diradicaloids, often regarded as an undesired or a decomposition feature, can be utilized to create function, ,− develop new methods, , and deepen our chemical concepts. , …”

An All-Organic Photochemical Magnetic Switch with Bistable Spin States

“…The diradicaloid character of the thermally accessible singlet state O S is enhanced for the open form which is represented by y values of 0.12 and 0.84 for 1a-O and 1b-O , respectively. Such ground-state triplet diradicals are rare because the double spin-polarization effect turns the vast majority of diradicals into ground-state singlets with a thermally accessible triplet state. − However, a triplet ground state, as found in our helical switch system, is desirable for obtaining a maximum response of the EPR-active form.…”

The taming of Clar's hydrocarbon

“…In 2017, pristine triangulene was generated, visualized and studied on a single-molecule level using scanning probe microscopy on various surfaces under ultra-high vacuum by Pavliček et al 32 In 2021, two substituted triangulene derivatives persistent in oxygen-free solutions at room temperature were synthesized and characterized independently by Shintani et al and our research team (Juríček et al ). 33,34 Considering the great potential of triangulene and related compounds to be employed as building blocks in quantum spin materials, demonstrated recently by Fasel et al (2021), 35 and the methodology that is now available for the in-solution synthesis of triangulene derivatives, we think it is timely to reflect on the development of triangulene chemistry over the past seven decades, as we finally enter the era of solution-processed bulk materials built from persistent open-shell graphene fragments.…”