Charge transport parameters for carbon based nanohoops and donor–acceptor derivatives

Abstract

The effect of donor–acceptor (D–A) moieties on magnitudes such as reorganization energies and electronic couplings in cycloparaphenylene (CPP) carbon based nanohoops (i.e. conjugated organic molecules with cyclic topology) is highlighted via model computations and analysis of the available crystalline structure of N,N-dimethylaza[8]CPP.

[4]Cyclo‐N‐ethyl‐2,7‐carbazole: Synthesis, Structural, Electronic and Charge Transport Properties

“…[11] In 2019, theoreticalc alculations have predicted the strongp otentialo fC PPs and donor-acceptor CPPs as high mobilitym aterials. [12,13] However,a nd despite the fantastic development of organic electronics technology in the last twenty years, [14] only very few exampleso fn anorings incorporation in organic electronic devices have been reported so far. [15,16] Bridging the gap between organic electronics and nanorings appears hence as an appealing challenge.…”

Theoretical Insights for Materials Properties of Cyclic Organic Nanorings

“…Theoretical studies have also shed light about the relative importance of both molecular magnitudes (reorganization energies and electronic couplings) on final mobility values of crystalline samples, with reorganization energies decreasing with the nanoring size, [ 111 ] as expected due to the larger electronic delocalization, and moderate (and almost constant) electronic coupling values along the sequence of the 5‐12CPPs systems studied. [ 66 ] The detailed analysis of the calculated electronic couplings (e.g., 6CPP, 8CPP, and 12CPP) along all the possible supramolecular paths [ 112 ] (see again Figure 4) allows one to reach the following conclusions: i) the electronic couplings are generally negligible for tubular‐like arrangements, due to the exponential decay with the intermolecular distance, which is necessarily large here due to the CH⋅⋅⋅CH mutual orientations of these superimposed dimers; ii) the herringbone‐like dimers do not give rise to the largest values neither; and iii) the slipped face‐to‐face orientation of the dimers found between layers of molecules leads to the highest values found, thus identifying the high‐mobility crystalline plane. Briefly, for these nanorings, the inter‐layer charge transport mechanism (due to the favorable slipped‐lateral dimer arrangements found) is more efficient than the intra‐layer counterpart.…”

“…Prompted by the availability of the crystal structure of N , N ‐dimethylaza‐8‐CPP, DMA‐8‐CPP in the following, the semiconducting properties of this molecule has also been recently investigated [ 112 ] and compared to 6CPP, 8CPP, and 12CPP. Note that another CPP derivative, namely 4‐cyclo‐ N ‐ethyl‐2,7‐carbazole also with radially oriented π‐orbitals, has been recently incorporated [ 232 ] in an organic field‐effect transistor (OFET) with low experimental mobilities () but in agreement with those experimentally found for 10CPP [ 233 ] too.…”

“…The experimental synthesis of donor–acceptor (D–A) compounds [ 288–290 ] has propelled the study of the photophysical and semiconducting properties of this set of materials. [ 112,125,291 ] Figure 7 shows some functionalization strategies of CPPs leading to N‐doped systems. An inmediate consequence of the D–A fragments introduced is the localization of the HOMO and LUMO on different parts of the molecule, thus poorly overlapping and consequently reducing the HOMO‐LUMO energy gap with respect to the undoped CPP systems.…”

“…">1.The chemical and topological origin of the radical‐like nature of closely related nanorings (i.e., cyclacenes [CCs]) compared with CPPs, [ 103,104 ] and the possible implications for the envisioned growth of armchair or zigzag CNTs [ 105,106 ] ; 2.The comprehension of the driving forces for the supramolecular packing and cohesive energies of these systems as a function of their size, [ 107 ] therefore opening a way to tune their supramolecular structure to access solid‐state CNT‐like structures via the adequate functionalization, [ 108–110 ] and the determination of the preferred charge‐transfer career paths [ 111,112 ] ; 3.The differences between pristine and substituted CPPs, [ 113–121 ] with emphasis on intra‐molecular donor‐acceptor compounds [ 122–124 ] displaying fluorescent and semiconducting properties upon specific functionalization [ 125 ] ; …”