An efficient and versatile synthetic strategy toward cruciform anthanthrene compounds using Sonogashira couplings steps was developed. Acetylenic linkers were used to effectively extend the π-conjugation of polycyclic anthanthrone and anthanthrene compounds and tune their optoelectronic properties. Structure-property relationships supported by DFT calculations indicated more effective π-conjugation along the 6,12 axis than along the 4,10 axis. These molecules displayed strong J-aggregation both in solution and in the solid state and proved to be highly photostable with reversible redox processes, which are properties of interest in materials sciences.

New anthanthrone-based polycyclic scaffolds possessing peripheral crowded quinodimethanes have been prepared. While the compounds adopt a closed-shell butterfly-shaped structure in the ground state, a curved-to-planar fluxional inversion is accessible with a low energy barrier through a biradicaloid transition state. Inversion is primarily driven by the release of strain associated with steric hindrance at the peri position of the anthanthrone core; a low-lying diradical state is accessible through planarization of the core, which is attained in solution at moderate temperatures. The most significant aspect of this transformation is that planarization is also achieved by application of mild pressure in the solid state, wherein the diradical remains kinetically trapped. Complementary information from quantum chemistry, H NMR, and Raman spectroscopies, together with magnetic experiments, is consistent with the formation of a nanographene-like structure that possesses radical centers localized at the exo-anthanthrone carbons bearing phenyl substituents.

Narrow thiophene-edged graphene nanoribbons (GNRs) were prepared from polychlorinated thiophene-containing poly(p-phenylene)s using the photochemical, metal-free cyclodehydrochlorination (CDHC) reaction. H NMR and Raman spectroscopy confirmed the structures of the GNRs. The regioselectivity of the CDHC reaction allows the preparation of both laterally symmetrical and unsymmetrical GNRs and, consequently, the modulation of their optical and electronic properties.

We studied structure, molecular orientation, morphology, and electrostatic properties of mixed self-assembled monolayers (SAMs) comprised of alkanethiolates (ATs) which are modified by a dipolar ester group embedded into the alkyl backbone at two different orientations, namely, with the dipole directed upward and downward from the substrate. The packing density and molecular orientation in these SAMs were found to be similar to those of the “parent” single-component monolayers. Applying X-ray photoelectron spectroscopy (XPS) as a morphology tool, we could estimate that the mixed SAMs represent homogeneous intermolecular mixtures of both components, down to the molecular level, excluding existence of “hot spots” for charge injection. The analysis of the C 1s XPS spectra and the work function data suggests that the composition of the mixed SAMs fully mimicked the mixing ratio of both components in the solutions from which these SAMs were prepared, which suggests a minor role of the dipole–dipole interaction in the overall balance of the structure-building forces. Varying this composition, work function of the gold substrate could be tuned linearly, in controlled fashion within a ∼1.1 eV range, between the ultimate values for the single-component monolayers with a fixed orientation of the embedded ester group, namely, 3.83 and 4.92 eV. This adjustment could be performed keeping the chemical composition at the SAM-ambient interface unchanged, which, along with tunability and homogeneity of these films, is a great advantage of the midchain substituted monolayers, qualifying them for energy-level alignment in model systems and organic electronics devices.

New anthanthrone-based polycyclic scaffolds possessing peripheral crowded quinodimethanes have been prepared. While the compounds adopt ac losed-shell butterflyshaped structure in the ground state,acurved-to-planar fluxional inversion is accessible with al ow energy barrier through ab iradicaloid transition state.I nversion is primarily driven by the release of strain associated with steric hindrance at the peri position of the anthanthrone core;alow-lying diradical state is accessible through planarization of the core, which is attained in solution at moderate temperatures.T he most significant aspect of this transformation is that planarization is also achieved by application of mild pressure in the solid state,w herein the diradical remains kinetically trapped. Complementary information from quantum chemistry, 1 HNMR, and Raman spectroscopies,t ogether with magnetic experiments,i sc onsistent with the formation of an anographene-like structure that possesses radical centers localized at the exo-anthanthrone carbons bearing phenyl substituents.Thestudyofnanographenediradicalshasbeenthesubjectof intense research because of the outstanding spin and electronic properties of graphene (of which nanographenes are amolecular version), [1] the intrinsic beauty of stable high-spin molecules,a nd the opportunity to investigate fundamental aspects of chemical bonding. [2] Several strategies for attaining such biradicaloid molecules with varying degrees of diradical character [3] have been developed and some are presented in Scheme 1. Such strategies include:1 )accumulation of proaromatic (that is,q uinodimethanes or quinoidal) rings in oligomeric structures,which leads to the formation of asinglet diradical by the recovery of Hückel aromaticity; [4,5] 2) construction of antiaromatic molecules; [3a,6] and 3) design of nanographenes with appropriate zig-zag edge states (that is,m etallic or half-metallic) such as acenes and fused acenes. [7,8] Singlet diradical molecules are characterized by unique optoelectronic properties [2c, 5a, 9] relevant to the field of nonlinear optics, [10] spintronics, [11] and organic photovoltaics, [12] among others.H owever,t oe nable the exploration of the unique properties of diradicals in ap ractical setting it is necessary to consider their chemical stability.Incases 1) and 2) above,smaller oligomers are highly stable molecules owing to af ull bonding electronic configuration, whereas diradical character is observed in longer oligomers. [4,5] Yett he preparation of such elongated p systems often requires tedious synthesis and the oligomers suffer from poor stability. Following the pioneering work of Hirai and coworkers on the observation of af airly stable triplet carbene, [13] the anthracene substructure has been utilized in the design of biradicaloid molecules. [14]