Ausgedehnte, benzanellierte Oligo‐BODIPYs: In nur drei Schritten zu einer Serie planarer, bogenförmiger Nahinfrarot‐Farbstoffe

Abstract

Wir präsentieren eine einfache Dreistufensynthese, welche anhand eines Oligomerisierungs‐ und anschließenden Oxidationsschrittes zu vollständig konjugierten, benzanellierten Oligo‐BODIPYs führt, ausgehend von üblichen BODIPY‐Vorstufen. FeCl3 dient hierbei als effizientes, bifunktionales Oxidans, um einen mehrstufigen Cyclisierungs‐ und Unsättigungsprozess im Eintopfverfahren anzustoßen. Angewendet auf ethylenverbrückte dimere, trimere und oligomere Spezies überführt dieser Ansatz flexible Ethanoeinheiten in versteifende Benzanellierungen zwischen den unsubstituierten β‐Positionen einzelner BODIPY‐Untereinheiten. Die strukturelle Integrität wurde mittels Röntgenstrukturanalyse verifiziert, und alle Verbindungen wurden einer detaillierten photophysikalischen sowie elektro‐ und computerchemischen Analyse unterzogen. Die Anregungsenergie des dominanten S1‐Zustandes konvergiert schrittweise an ein strukturspezifisches Absorptionslimit, was sich in einer ausgeprägten Rotverschiebung von ca. 500 nm (BODIPY‐Monomer) bis hin zu 955 nm (Oktamer) mit Extinktionskoeffizienten von ca. 500 000 m−1 cm−1 widerspiegelt.

Electrochemical Diselenation of BODIPY Fluorophores for Bioimaging Applications and Sensitization of 1O2

“…70 nm to longer wavelengths compared to the respective precursors, indicating that the selenium atom plays a significant role in tuning the emission maxima of these compounds. In addition, no apparent pattern suggesting a significant charge transfer character in the ground and excited states is observed, consistent with preceding reports for other BODIPY derivatives [1f,3d,g] . These compounds exhibited modest fluorescence quantum yields (~0.3 %), as previously observed for selenium‐based BODIPYs [7c–e,i,8a,c,9] .…”

“…In this instance, the dual emission is anticipated to arise from two separate vibrational structures present in the excited state. The fluorescence lifetimes of the precursors (~4 ns) are in accordance with what is expected for BODIPY derivatives [3g] . On the other hand, the selenium‐based BODIPYs showed shorter fluorescence lifetimes, ranging from 2.24 to 0.32 ns, with an average lifetime of ca.…”

“…This can still be useful for turn off‐on sensing, as observed in several compounds, [18] and even in selenium‐containing BODIPY‐based ones [19] . Finally, the selenium derivatives exhibited significantly larger Stokes shifts (~2000 cm −1 ) compared to the starting BODIPYs (~500 cm −1 ), previously reported compounds (~400 cm −1 ), [1f,3d,g] and even BODIPY lipid probes, that usually show a strong overlap between the fluorescence and absorption spectra, [20] resulting in a substantial reduction of the inner filter effect. The selenium‐containing BODIPYs showed broad emission compared to reported BODIPYs, which could be used to enable imaging [21a] .…”

Double π‐Extended Undecabenzo[7]helicene

“…Extension of p-electron delocalization is arguably one of the most important strategy for designing and exploring novel aromatic compounds for different applications. [1] It has been actively implemented for upgrading essentially all popular chromophores and fluorophores,s uch as porphyrin, [2] naphthalene/perylene diimide, [3] rhodamine, [4] and boron dipyrromethene, [5] to name af ew.I nt his regard, p-extended three dimensional synthetic nanographene (NG) is ap articularly attractive field, allowing access to many conjugated polycyclic aromatic hydrocarbons (PAHs) with appealing p-topology and unusual photophysical properties. [6][7][8][9] However,i nc ontrast to the common small planar aromatic compounds, p-extension in large three dimensional PA Hs is intrinsically challenging,because of substantial strain involved as well as the difficult chemistry to connect and fuse multiple structural subunits in ananoscale three dimensional molecular entity.T ake the multiple [n]helicene, [10][11][12][13][14][15][16] akind of actively studied chiral NG,a sa ne xample,m ost precedents feature at least one narrow "bottleneck" benzene region ( Figure S3), which is expected to limit the extent of pconjugation, and thereby will affect their optical and electronic properties.F ull p-extension of their helicene subunit has rarely been achieved.…”

Transition-Metal-Catalyzed C–H Activation Reactions for the Creation and Modification of Organic Fluorophores

“…143 In 2021, Werz and co-workers synthesized oligo BODIPYs (oligomers of BODIPYs) from simple BODIPY monomers via a FeCl 3 -mediated Scholl oxidation process. 144 The developed oligo-BODIPY exhibit a strong absorption shift (955 nm) as compared to the BODIPY monomer (500 nm).…”