Substituent effects on the optical properties of naphthalenediimides: A frontier orbital analysis across the periodic table. Issue 2 (7th October 2015)

• Record Type: Journal Article
• Authors: Mulder, Joshua R.; Guerra, Célia Fonseca; Slootweg, J. Chris; Lammertsma, Koop; Bickelhaupt, F. Matthias
• Is Part Of: Journal of computational chemistry. Volume 37:Issue 2(2016)
• Page Start: 304
• Page End: 313
• Publication Date: 2015-10-07
• Subjects: naphthalene diimides -- time‐dependent density functional theory -- electronic excitations -- long‐range corrected functional -- orbital electronic structure; Chemistry -- Data processing -- Periodicals; 542.85
• DOI: 10.1002/jcc.24197
• Languages: English
• ISSNs: 0192-8651

Abstract

Abstract : A comprehensive theoretical treatment is presented for the electronic excitation spectra of ca. 50 different mono‐, di‐, and tetrasubstituted naphthalenediimides (NDI) using time‐dependent density functional theory (TDDFT) at ZORA‐CAM‐B3LYP/TZ2P//ZORA‐BP86/TZ2P with COSMO for simulating the effect of dichloromethane (DCM) solution. The substituents XHn are from groups 14–17 and rows 2–5 of the periodic table. The lowest dipole‐allowed singlet excitation (S0 –S1 ) of the monosubstituted NDIs can be tuned from 3.39 eV for F to 2.42 eV for TeH, while the S0 –S2 transition is less sensitive to substitution with energies ranging between 3.67 eV for CH3 and 3.44 eV for SbH2 . In the case of NDIs with group‐15 and −16 substituents, the optical transitions strongly depend on the extent to which XHn is planar or pyramidal as well as on the possible formation of intramolecular hydrogen bonds. The accumulative effect of double and quadruple substitution leads in general to increasing bathochromic shifts, but the increased steric hindrance in tetrasubstituted NDIs can lead to deformations that diminish the effectiveness of the substituents. Detailed analyses of the Kohn–Sham orbital electronic structure in monosubstituted NDIs reveal the mesomeric destabilization of the HOMO as the primary cause of the bathochromic shift of the S0 –S1 transition. © 2015 Wiley Periodicals, Inc. Abstract : It is shown through TDDFT explorations that naphthalenediimide's (NDI's) strong S0 –S1 transition offers excellent opportunities for tuning its absorption frequency through substituents. Kohn–Sham MO analyses reveal that the S0 –S1 gap can be reduced by pushing the overall HOMO up in energy using a more electropositive substituent. The S0 –S1 transition can be pushed beyond the "700 nm barrier" which is crucial for developing antenna molecules absorbing near‐infrared photons in the solar spectrum.