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Adding nitro groups to aromatic compounds usually quenches their fluorescence via intersystem crossing (ISC) or internal conversion (IC). Herein, we investigated centrosymmetric 1,4-dihydropyrrolo[3,2-b]pyrroles linked to variously substituted nitro-heteroaryls. A 1,4-orientation of the nitro substituent versus the electron rich 1,4-dihydropyrrolo[3,2-b]pyrrole core invokes a strong fluorescence in non-polar solvents and intense two-photon absorption while a 1,3-orientation of push-pull substituents results in a dramatic hypsochromic shift of absorption, weak, bathochromically shifted emission and weak two-photon absorption. The combined experimental and computational study indicates that the primary responsible factors are: (1) the difference in electron density distribution in the LUMO; (2) the difference in mu 10. IC is a dominant mechanism of non-radiative dissipation of energy in all these dyes but as long as the distribution of electron density within the HOMO and LUMO is delocalized on the 1,4-dihydropyrrolo[3,2-b]pyrrole core as well as on the nitroaromatic moieties its rate is slower than the fluorescence rate in non-polar solvents., Funding Agencies|Foundation for Polish Science (TEAM) [POIR.04.04.00-00-3CF4/16-00]; National Science Centre, Poland [2017/25/Z/ST2/03038]; OPUS [2020/37/B/ST4/00017]; European Union [101007804]; JSPS KAKENHI [21H01887]; Ministry of Education and Science of Ukraine [0121U107533]; Academy of Finland [346369]; Swedish Research Council [2022-06725]; Swedish Research Council [2020-04600]; Olle Engkvists Stiftelse (Sweden) [212-0136]