We theoretically characterize a series of substituted cycloparaphenylene nanohoops to study the effect of incorporating an electron-withdrawing group into their cyclic structure. We systematically vary the nature, position, and number of nitrogen-containing acceptor groups in both neutral (pyridine) and charged forms (pyridinium and methylpyridinium) to provide insights into how this functionalization affects the structural, electronic, and optical properties of these systems. We focus also on the singlet-triplet energy difference, with low values found, which might pave the way to further applications in the field of devices for light-emitting applications providing a potential class of TADF-based emitters. K E Y W O R D S density functional theory, donor-acceptor cycloparaphenylenes, optoelectronic properties, TD-DFT, thermally activated delayed fluorescence | I N TR ODU C TI ONOrganic Electronics is a field of rapid growth attracting interest from interdisciplinary domains including electronics & engineering, chemistry, physics, and materials science, not to mention the great commercial interest toward its applications. [1,2] The facile tunability of organic molecules has paved the way for a wealth of organic-based materials to be synthesized with novel key properties. Already, small organic molecules find their place in photovoltaic cells, [3,4] light-emitting transistors, [5][6][7][8][9] and diodes, [10][11][12] to name just a few of these applications. The flexibility of organic materials over inorganic has enabled the birth of the "soft electronics" market, including devices that can twist, bend or mould to any surface or textile. With so many possibilities arising from unique properties of organic molecules, the future of organics appears bright: not only do organic materials promise more innovative technologies but also are far more sustainable (organic molecules are abundant, easily synthesized and potentially Int J Quantum Chem. 2018;118:e25562.

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.