Spiroconjugated Tetraaminospirenes as Donors in Color‐Tunable Charge‐Transfer Emitters with Donor‐Acceptor Structure

Grenz, David C.; Rose, Daniel M.; Wössner, Jan S.; Wilbuer, Jennifer; Adler, Florin; Hermann, Mathias; Chan, Chin‐Yiu; Adachi, Chihaya; Esser, Birgit

doi:10.1002/chem.202104150

Cited by 3 publications

(2 citation statements)

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“…Molecules with a donor-acceptor structure separated by a bridge have the advantages of being used as charge transfer materials. [1,2,3] Transfer of charge is the result of an electron ionization or excitation when the nucleus is frozen. [4,5] The phenomenon at the molecular level plays a fundamental role in many areas like physical, chemical, biological, material sciences with vital applications.…”

Section: Introductionmentioning

confidence: 99%

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DFT Studies on the Molecular Structure, Regioisomerism, Ground and Excited state Charge Transfer Properties of Spiro‐heterocycles

Anumol¹,

Jose²,

Joy³

2022

ChemistrySelect

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The electronic structure, stereochemical aspects and charge transfer properties of the spiro compound (5S,8S) spiro‐{6‐phenyl‐1‐aza‐3‐oxa‐7‐thia‐bicyclo[3,3,0]‐octene‐8,3’(2’H)‐indol}‐2’‐one (spiro bicyclo adduct) synthesized using the multi‐component reaction via 1,3‐dipolar cycloaddition of isatin and thioproline with the dipolarophile phenylacetylene have been studied. The two lowest energy regio‐isomers of the spiro heterocycle formed from the stereospecific dipolar reaction have been analysed along with the electron‐withdrawing and releasing substituents using DFT method at the CAM‐B3LYP/6‐311++G(d,p) level of theory. The atomic charges and the stabilization energy due to the intramolecular charge delocalization process calculated using the natural orbitals at the different molecular sites reveal the different donor‐acceptor interactions occurring in the system. The intramolecular electronic transitions (specifically n to π* and π to π*) is found to occur from the localized donor end component to the acceptor end components in the multi‐component system. The hole produced by the ionization of the entities is found to migrate from the thioproline component to the phenyl acetylene part in a time scale of around 4 fs. The electron‐withdrawing and donating substituents on the spirobicyclo adduct have been proven to tune the excited and ground state charge transfer properties uniquely. The results can shed light on how multi‐component reactions can be directed to produce spiro adducts with versatile applications.

show abstract

Section: Introductionmentioning

confidence: 99%

“…Molecules with a donor‐acceptor structure separated by a bridge have the advantages of being used as charge transfer materials [1,2,3] . Transfer of charge is the result of an electron ionization or excitation when the nucleus is frozen [4,5] .…”

Section: Introductionmentioning

confidence: 99%

DFT Studies on the Molecular Structure, Regioisomerism, Ground and Excited state Charge Transfer Properties of Spiro‐heterocycles

Anumol¹,

Jose²,

Joy³

2022

ChemistrySelect

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Control of Photoinduced Charge Transfer Through Selective Cyanation of Spirofluorene‐Bridged N‐Heterotriangulenes

Jocic,

Galindo,

Weidlich

et al. 2024

Advanced Optical Materials

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A series of selectively cyanated spirofluorene‐bridged N‐heterotriangulenes (N‐HTAs) with three to nine cyano groups are synthesized via a newly developed synthetic strategy. X‐ray crystallographic analysis of the compounds revealed a tripod‐like molecular shape with the fluorenyl moieties arranged in a perpendicular fashion around the nitrogen‐centered N‐HTA core. The solid state packing is found to be strongly influenced by the dipolar cyano functions. Under electrochemical conditions, the N‐HTA core is prone to undergo a reversible one‐electron oxidation toward the nitrogen‐centered radical cation, which becomes increasingly difficult as the number of the cyano acceptors, and consequently the ionization potential, increases. While a clear bathochromic shift is observed in the steady‐state UV–vis absorption spectra, the fluorescence behavior is complex and strongly dependent on the position and number of the cyano groups. The compound with six cyano functions at the fluorenyl flanks is unique within the series and shows a broad emission maximum at 499 nm and an unusually large Stokes shift of 10 171 cm−1. Time‐resolved absorption and fluorescence measurements, supported by quantum chemical calculations, identified this spectroscopic signature to originate from fast and robust photoinduced intramolecular charge transfer.

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