Computational design of improved two‐photon active caging compounds based on nitrodibenzofuran

Abstract

Nitrodibenzofuran (NDBF) has recently been established as photolabile protecting group and efficiently used as two-photon active cage. In this work, a computational approach is exploited to rationally design improved two-photon active caging groups based on this NDBF chromophore. For this objective, first the two-photon absorption (TPA) properties of NDBF are investigated in detail and a suitable theoretical approach for the reliable simulation of TPA spectra of this class of compounds is identified. Then, virtual chemical modifications are performed by introduction of substituents at the chromophore and replacement of the central furan ring by pyrolle, thiophene, and borrole heterocycles. Subsequently, the TPA properties of the resulting compounds are computed, and the influences of the chemical modifications on TPA properties investigated in detail. The most promising candidates with largely increased two-photon uncaging efficiencies are dimethylamino-substituted derivatives of NDBF, nitrodibenzopyrrol, and nitrodibenzothiophene.

From One‐Photon to Two‐Photon Probes: “Caged” Compounds, Actuators, and Photoswitches

“…Structural factors that influence the TPA of a molecule have been studied extensively and are now reasonably well understood;7, 8 the TPA cross‐section can now be predicted to a fairly high precision by computation 9. The key parameters of increased TPA are extended conjugation (Figure 2) and the presence of strong donor and/or acceptor couples that promote strong internal charge transfer (ICT; Figure 2);10, 12 The strength of the polarization can also be evaluated by using Hammet parameters 11…”

A red-shifted two-photon-only caging group for three-dimensional photorelease

“…Due to calculations with the DFT/B3LYP method and a 6-31*G basis set for the ground state equilibrium structures and TDDFT/BHLYP for exited states the dipolar structure should be red-shifted and have an increased δ a . 26 Despite the availability of sophisticated computational methods the optimisation of 2P-chromophors remains a formidable challenge.…”

Von Ein‐ zu Zwei‐Photonen‐Sonden: photoaktivierbare Reagentien, Aktuatoren und Photoschalter

“…Die strukturellen Faktoren, die die Zwei-PhotonenAbsorption eines Moleküls beeinflussen, wurden ausführlich untersucht und sind gut verstanden; [7,8] TPA-Querschnitte kçnnen heute mit dem Computer mit recht hoher Präzision vorhergesagt werden. [9] Die Schlüsselparameter für eine hohe Zwei-Photonen-Absorption sind ausgedehnte Elektronenkonjugation (Abbildung 2) und die Gegenwart von starken Donor-und/oder Akzeptorpaaren, die einen starken internen Ladungstransfer (ICT; internal charge transfer) vermitteln (Abbildung 2). [10] Die Stärke der Polarisation kann auch mithilfe von Hammett-Parametern ermittelt werden.…”