Synthesis and Functionalization of Novel Tetrathia[7]helicenes as New Push-Pull Systems

Licandro, Emanuela; Rigamonti, Clara; Ticozzelli, Maria Teresa; Monteforte, Marco; Baldoli, Clara; Giannini, Clelia; Maiorana, Stefano

doi:10.1055/s-2006-950222

Cited by 4 publications

(4 citation statements)

References 5 publications

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“…Alk‐F2 and Alk‐CF‐F2 were suspended or dissolved, respectively, in benzene and a catalytic amount of PhSSPh was added; [31] the mixtures were irradiated, in a 250 mL photo‐reactor equipped with an immersion, quartz‐coated, 125 W medium‐pressure mercury lamp for about 8 h until disappearance of the starting reagent. The reaction proceeded with comparable or slightly lower rate with respect to that of the ( E )‐ Alk‐H [21c] while resulted much slower compared to the rapid photocyclization of ( Z )‐ Alk‐C3 to Heli‐C3 [21b,28] …”

Section: Resultsmentioning

confidence: 99%

“…Instead, Alk‐C3 , given its Z configuration, efficiently and quickly converts into Heli‐C3 [21b,28] in diluted solution at RT along the excitation beam path of the Xe lamp (Figure S1, λ exc. =350 nm, the excitation and emission profiles recorded for Alk‐C3 match those of Heli‐C3 ).…”

Section: Resultsmentioning

confidence: 99%

“…Compounds Alk‐H , [21c] Alk‐C3 , [21b] Alk‐CF , [27] Heli‐C3 [21b] and Heli‐CF [36] have been previously reported and synthesized accordingly. Unless otherwise specified, all reactions were performed under nitrogen atmosphere.…”

Section: Methodsmentioning

confidence: 99%

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Sparkling Organic Phosphorescence from Fluorinated Tetrathia[7]helicenes: Synthesis and Photophysical, Electrochemical and Computational Studies

Bossi¹,

Mussini

Farinola

et al. 2023

Chemistry A European J

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Structure-property correlations in the thiahelicene family are often not trivial beacuse most of the functional groups present on the helical scaffold modify the conjugation size of the π-system. Selecting fluorine-containing groups to provide strong inductive effects without interacting with lowlying orbitals of the system could be the way to overcome the issue. Here we report a study on three fluorinefunctionalized tetrathia[7]helicenes, highlighting interesting correlations between the position of the functional groups and the conjugated skeleton properties. Helicenes Heli-F2 and Heli-CF-F2 were prepared by photoinduced isomerization-electrocyclization (the Mallory photocyclization) of the corresponding fluorinated benzodithienyl-ethenes Alk-F2 and Alk-CF-F2, which were prepared in high yields through stereo-conservative Stille reaction. Notably these helicenes were found to display green phosphorescence around 530-550 nm, and the studies suggest an efficient spin-orbit coupling mechanism in these high-energy triplet nonplanar conjugated molecules. Both helicenes and their precursors were thoroughly characterized by means of optical and electrochemical measurements, while DFT calculations enable a rationale on their structure-property correlations to be defined.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Sparkling Organic Phosphorescence from Fluorinated Tetrathia[7]helicenes: Synthesis and Photophysical, Electrochemical and Computational Studies

Bossi¹,

Mussini

Farinola

et al. 2023

Chemistry A European J

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“…Indeed, helicenes are ortho -annulated polycyclic aromatic compounds endowed with an inherently chiral π-conjugated system which have attracted considerable attention because of their unique physicochemical properties and potential applications in different areas of science. − On the other hand, reacting π-helicene scaffolds with metals can significantly modify specific properties, obtaining a structural variety that however retains the defining features of the helical structure. In this context, tetrathia[7]helicenes (7-TH), in which the thiophene rings are fused to alternating benzene rings to form a configurationally stable helix, are emerging as the most promising systems, also thanks to the reliable functionalization of the terminal thiophene rings of the 7-TH scaffold − that allows the introduction of a diversity of functional groups, including those with an efficient coordinating ability (e.g., cyano and phosphane , ). Thus, the 7-TH nitrile derivatives were used as monodentate ligands in the synthesis of the corresponding Ru(II) and Fe(II) complexes that have been shown to be interesting candidates for optoelectronic purposes.…”

Section: Introductionmentioning

confidence: 99%

Dirhenium Coordination Complex Endowed with an Intrinsically Chiral Helical-Shaped Diphosphine Oxide

et al. 2018

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A one-pot, multicomponent strategy was used to synthesize the first example of the dirhenium carbonyl coordination complex 2 , in which the two metal atoms are connected through a chiral helical-shaped diphosphine oxide. Thanks to the flexibility of the helix of helicene 1 , complex 2 was isolated in quite a good yield as a stable compound. It was characterized by analytical and spectroscopic techniques as well as by single-crystal X-ray analysis, which confirmed the chemical structure and the peculiar architecture of 2 . In addition, computational studies were in agreement with the transitions observed in the experimental UV–vis spectrum, revealing the presence of two bands with maxima at about 520 (metal-to-ligand charge transfer) and 400 nm (IL).

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Benzodithienyl Silanes for Organic Electronics: AIE Solid‐State Blue Emitters and High Triplet Energy Charge‐Transport Materials

Bossi¹,

Arnaboldi

Castellano

et al. 2020

Advanced Optical Materials

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the design and preparation of organic semiconducting frameworks and the thoroughly understanding of the structureproperty-function correlations. Advanced microscopic techniques were lately employed to deepen the comprehension of the solid-state supramolecular organization, intermolecular interactions, and interfacial phenomena linked to material processing. [3,4] This is the case of OLEDs which, given their potential to achieve 100% electron to photon conversion efficiency, are the reference technology employed in energy saving flat panel displays and promising alternative to develop solid-state lighting. OLEDs, in their simplest configuration, are composed of a stack of different organic or organometallic semiconducting materials layered, with appropriate techniques, between two electrodes. The electroluminescence (EL) process, leading to light emission, is the result of recombination into the emitting layer of the charges, holes and electrons, injected from the transparent anode and the metal cathode. The charge recombination produces excitons which, trapped by the emissive material, radiatively decay with the emission of photons. The emissive layer (EML) is typically a dispersion of phosphorescent transition-metal complex emitters, mostly based on Ir(III) and Pt(II) metal ions, into an organic host material. [5−8] In recent years, a new paradigm emerged in OLED technology that is the use of pure organic compounds as dopant able to harvest, similarly to the transition-metal complexes, both singlet and triplet electrogenerated excitons, through the so called thermally activated delayed fluorescence (TADF). [9] In either cases, phosphorescent or TADF-OLEDs, the host material has to meet a complex profile of requirements, including: i) triplet excitation energy exceeding that of the emitter; ii) frontier energy orbitals matching those of the neighbor layers in order to trap charges (both electrons and holes) and transfer the excitation energy to the emitter; iii) stability under device operation; iv) ability to form an amorphous stable phase with good morphology; v) ease of large scale synthesis. [10−15] Extended π-conjugated fused aromatic molecules fit almost all the mentioned requirements due to their rigid π skeletons, A novel class of benzo[1,2-b:4,3-b′]dithienyl (BDT) silanes 1-3 in which a tetrahedral silicon atom connects two BDT units is developed as high triplet energy 3D-host. The photophysical and electrochemical properties of these structures are investigated, demonstrating that the peculiar features of the constituting BDT units are preserved in the corresponding silanes. All compounds display deep UV absorption (E g = 4.10-3.52 eV) and fluorescent emission (300-400 nm for 1 and 2, and 350-450 nm for 3). Phosphorescence is observed at low temperature and the respective T 1 states set at 2.65, 2.59, and 2.25 eV. Emission efficiency in solution is as high as 0.18 in 3. Compound 1 crystallizes in two monoclinic structures without relevant intrainter-molecular contacts; both display similar and intriguin...

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Synthesis and Functionalization of Novel Tetrathia[7]helicenes as New Push-Pull Systems

Cited by 4 publications

References 5 publications

Sparkling Organic Phosphorescence from Fluorinated Tetrathia[7]helicenes: Synthesis and Photophysical, Electrochemical and Computational Studies

Sparkling Organic Phosphorescence from Fluorinated Tetrathia[7]helicenes: Synthesis and Photophysical, Electrochemical and Computational Studies

Dirhenium Coordination Complex Endowed with an Intrinsically Chiral Helical-Shaped Diphosphine Oxide

Benzodithienyl Silanes for Organic Electronics: AIE Solid‐State Blue Emitters and High Triplet Energy Charge‐Transport Materials

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