Doubly N‐Fused [24]Pentaphyrin Silicon Complex and Its Fluorosilicate: Enhanced Möbius Aromaticity in the Fluorosilicate

Ishida, Shin; Kim, Jun Oh; Kim, Dongho; Osuka, Atsuhiro

doi:10.1002/chem.201603598

Cited by 21 publications

(13 citation statements)

References 74 publications

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“…The UV/Vis/NIR absorption spectroscopic titration of 1 with tetrabutylammonium difluorotriphenylsilicate (TBAT) in CH 2 Cl 2 was a one‐step deprotonation process. As shown in Figure b, addition of TBAT to a solution of 1 in CH 2 Cl 2 caused spectral changes with several isosbestic points at 373, 407, 641, and 694 nm to show a clean conversion of 1 to most probably its mono‐deprotonated species, featuring a decrease of the absorption bands at 665 and 1063 nm and an increase of the absorption band at 1316 nm.…”

Section: Figurementioning

confidence: 99%

Structural and Aromaticity Control of [34]Octaphyrin(1.1.1.0.1.1.1.0) by Protonation and Deprotonation

Naoda

Osuka

2017

Asian J Org Chem

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The structurala nd aromaticity control of hexakis(pentafluorophenyl) [34]octaphyrin(1.1.1.0.1.1.1.0) 1 was examined by protonation and deprotonation. Protonation of 1 with methanesulfonica cid (MSA) induced as tructural change from af igure-eightt oarectangular shape,a ccompanied by an aromaticity change from nonaromatict o strong Hückel aromatic. Deprotonation of 1 with tetrabutylammonium difluorotriphenylsilicate (TBAT) or fluoride (TBAF) produced amono-deprotonated specieswith asimilar figure-eight conformation andn onaromaticity.Recently,i ncreasing attention has been focused on expanded porphyrins in light of their fascinating properties such as large p-conjugations, conformationalf lexibilities, near-infrared (NIR) absorption, rich metal coordination,r adical-stabilizing abilities, and potential tos erve as platforms of Mçbius aromatic and antiaromatic molecules, which are not shared with porphyrin. [1] Since our serendipitousd iscoveryo faone-pot synthesis of meso-aryl-substituted expanded porphyrins, [2] we have actively exploredt heir properties. Sessler et al., [3] Latos-Grażyń ski et al., [4] Chandrashekar et al., [5] Anand et al., [6] and others [7] made continuous efforts to develop novel features of expanded porphyrins. Through these efforts, it is now clear that expanded porphyrins are an effectivea romaticity-switching motif.Naturally,t he aromaticity of expanded porphyrins is heavily dependentu pon their conformations,a nd therefore conformational control of expanded porphyrins is crucial in the exploration of aromaticity-switching expanded porphyrins. So far,p rotonation, [8] deprotonation, [9] metal coordination [10] and solvents [11] have been used for conformational control of expanded porphyrins. Among these means, protonation and deprotonation are expected to be quite effective, sincet he conformations of expanded porphyrins are usually held by intramolecular hydrogen bonding between the amine-and imine-type pyrroles. Actually,p rotonation and deprotonation of meso-hexakis(pentafluorophenyl)

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Section: Figurementioning

confidence: 99%

Structural and Aromaticity Control of [34]Octaphyrin(1.1.1.0.1.1.1.0) by Protonation and Deprotonation

Naoda

Osuka

2017

Asian J Org Chem

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“…In the S 1 state of the Si IV complex 2 , intersystem crossing rarely occurs (see Figure S25); that is, less than one percent of molecules in the excited S 1 state flip their spin within a given lifetime of 7.3 ps (38 %) and 41 ps (61 %). These time constants can be assigned as the vibrational relaxation and electronic relaxation time, respectively, according to studies on 2 . The TA signals of the Ge IV complex 3 decayed with τ =58 ps (95 %) and showed a residual long‐lived component (5 %), corresponding to its S 1 and T 1 state, respectively.…”

Section: Methodsmentioning

confidence: 99%

Möbius Aromatic [28]Hexaphyrin Germanium(IV) and Tin(IV) Complexes: Efficient Formation of Triplet Excited States

et al. 2017

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[28]Hexaphyrin GeIV and SnIV complexes were synthesized in high yields by reactions of [28]hexaphyrin with GeCl4 or SnCl4 in the presence of triethylamine. Both complexes display distinct 28π Möbius aromatic character and possess a trigonal bipyramidal geometry at the central GeIV or SnIV atom. The equatorial hydroxy group of the GeIV complex was smoothly exchanged with neutral nucleophiles, such as phenol derivatives and thiophenol, with retention of configuration. In the SnIV complex, intersystem crossing to the T1 state is remarkably enhanced owing to the effective heavy‐atom effect, thus allowing the formation of the T1 state in high yield. The T1 states of the GeIV and SnVI complexes were found to be antiaromatic on the basis of the transient absorption features in line with the Baird rule.

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“…The current density and current pathways have been studied for doubly Möbius-twisted meso-trifluoromethyl-substituted hexaphyrins, which were synthesized by Shimizu et al, 208 which triggered a large number of experimental studies of twisted expanded porphyrins. 214,215,218,219,221,223,[237][238][239][240][241][242][243][244][245] NICS calculations as well as atom in molecules (AIM) and electron localization function (ELF) critical point approaches have been used in studies of the aromatic properties of the doubly-twisted [26]hexaphyrin and [28]hexaphyrin molecules. Topological studies showed that the synthesized hexaphyrin molecules are formally doubly-twisted molecules with a linking number L k of 2.…”

Section: Expanded and Twisted Porphyrinsmentioning

confidence: 99%

Theoretical studies as a tool for understanding the aromatic character of porphyrinoid compounds

et al.

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The scientific interest in porphyrinoid based materials is steady growing, since porphyrinoids are not only of biological relevance, but they also show interesting spectroscopic properties that link them to many possible applications such as near infrared dyes, photovoltaic dyes, field-effect transistors, nonlinear optical materials and nanoelectronic devices. 1-8 Biomedical applications of porphyrinoids are of particular importance specially for photomedical applications in cancer treatment, such as photodynamic therapy, multimodal imaging, drug delivery and biosensing. 9-12 Porphyrinoids show also an ability to form complexes with metals with unusual oxidation states and are therefore relevant for catalysis. 13-18 The classic porphyrin molecule can formally be regarded as four pyrrole rings connected to each other by methin bridges. 19 Depending on the localization of the two inner pyrrolic hydrogen atoms the molecule is labeled cis-or trans-porphyrin. However, at room temperature the inner hydrogens generally move around inside the porphyrin ring. 20,21 The more general term porphyrinoids is used for a class of molecules that share the classical porphyrin structure for the macroring but differ for example by bearing various substituents or heteroatoms. Classic porphyrins, chlorins and bacteriochlorins are aromatic molecules satisfying Hückel's (4n þ 2) p-electron count rule for aromaticity. 22,23 There is no doubt that aromaticity is an important concept in chemistry albeit it is still not fully understood and thus continuously under debate. 24-27 Theoretical calculations have shown that the aromatic pathways of

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Doubly N‐Fused [24]Pentaphyrin Silicon Complex and Its Fluorosilicate: Enhanced Möbius Aromaticity in the Fluorosilicate

Cited by 21 publications

References 74 publications

Structural and Aromaticity Control of [34]Octaphyrin(1.1.1.0.1.1.1.0) by Protonation and Deprotonation

Structural and Aromaticity Control of [34]Octaphyrin(1.1.1.0.1.1.1.0) by Protonation and Deprotonation

Möbius Aromatic [28]Hexaphyrin Germanium(IV) and Tin(IV) Complexes: Efficient Formation of Triplet Excited States

Theoretical studies as a tool for understanding the aromatic character of porphyrinoid compounds

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