- Photochemistry and photophysical properties of novel, unsymmetrically substituted metallophthalocyanines
-
A series of novel, unsymmetrically substituted metallophthalocyanines was synthesized, along with their symmetrically substituted analogs, and the effects of structure and metal substitution on their photophysical and photoredox properties were investigated. The macrocycles were synthesized using a mixed-condensation method followed by chromatographic separation of the resulting soluble products. They possess a catechol 'active site' and three tert-butyl groups for enhanced solubility. The ground- and excited- state photophysical properties of the free-base, Zn(II) and Pd(II) macrocycles were measured and compared with their symmetrically substituted (tetra[tert-butyl]) analogs. The efficiency with which these macrocycles sensitize the formation of singlet oxygen was determined and discussed in the context of the excited-state photophysical properties. Several examples of photoinduced electron transfer reactions with one- and two-electron acceptors are demonstrated and discussed. These soluble molecules can be tuned to optimize their photochemical and redox properties by varying the central metal, axial ligands and other substituents, thereby providing a series of molecules for the investigation of photodynamic therapy and photoinduced electron transfer mechanisms.
- Lawrence, David S.,Whitten, David G.
-
-
Read Online
- Photo-promoted Skeletal Rearrangement of Phosphine–Borane Frustrated Lewis Pairs Involving Cleavage of Unstrained C?C σ-Bonds
-
An unprecedented photo-promoted skeletal rearrangement reaction of phosphine–borane frustrated Lewis pairs, o-(borylaryl)phosphines, involving cleavage of an unstrained sp2C–sp3C σ-bond is reported. The reaction realizes an efficient
- Ito, Tatsuyoshi,Iwasawa, Nobuharu,Takaya, Jun
-
supporting information
p. 11913 - 11917
(2020/05/22)
-
- Design of twisted conjugated molecular systems towards stable multi-colored electrochromic polymers
-
Promising advancement of conjugated polymers in electrochromic devices require to design high-performance electrochromic polymers with rich color conversion and long-term stability under cyclic electrical loads. Here we report a new strategy in developing multi-colored electrochromic polymers with good stability via twisted conjugated molecular engineering. A series of twisted hybrid precursors are synthesized by coupling ortho-alkylenedioxybenzenes with EDOT units, and their corresponding polymers are facilely electrosynthesized at relatively low polymerization potentials. The structure-property relationships of such ortho-alkylenedioxybenzene-EDOT hybrid precursors and polymers are systematically elucidated via DFT calculations, spectral, morphological, electrochemical and spectroelectrochemical analysis, etc. We demonstrate that the dihedral angle between ortho-alkylenedioxybenzenes and EDOT moieties can substantially affect the electrochemical and electrochromic properties of polymers. As the dihedral angle and electron cloud density increases, these hybrid polymers display distinct multiple color switching nature and good overall performance including high coloration efficiency (>200 cm2 C?1), decent optical contrast (>45percent), fast switching (1 s), and excellent switching stability (96percent of optical contrast after 3500 cycling) under cyclic electrical loads. With these findings, this work will provide novel insights for rational design of stable and highly efficient multi-colored electrochromic polymers.
- Gu, Hua,Hu, Faqi,Jian, Nannan,Lin, Kaiwen,Liu, Ximei,Lu, Baoyang,Wu, Tao,Xu, Jingkun,Xue, Yu
-
-
- Asymmetric dearomative spirolactonization of naphthols using λ3-iodanes under chiral phase-transfer catalysis
-
The asymmetric phase-transfer catalytic effect of chiral Cinchona alkaloid-derived quaternary ammonium salts was investigated in the context of the λ3-iodane-mediated dearomative spirolactonization of naphthols. The scope and limitations of this methodology were evaluated using various substrates, which were converted into spirolactones in good yields and with enantiomeric excesses up to 58%.
- Antien, Kevin,Viault, Guillaume,Pouységu, Laurent,Peixoto, Philippe A.,Quideau, Stéphane
-
supporting information
p. 3684 - 3690
(2017/06/13)
-
- Access to Atropisomerically En-riched Biaryls by the Coupling of Aryllithiums with Arynes under Control by Homochiral Oxazolines
-
We report the preparation of axially stereoenriched biphenyls by the coupling of in situ generated aryllithiums and arynes using chiral oxazoline auxiliaries. The design of the aryne precursors, the choice of oxazoline and the reaction conditions were key to accessing the desired, highly substituted, atropisomerically enriched biarylic products. In one case, the two atropo-diastereomers could be obtained in isomerically pure form by column chromatographic separation and their absolute configurations established by X-ray crystallography. The stereoselectivity of the reaction seems to be governed by subtle parameters.
- Yalcouye, Boubacar,Berthelot-Bréhier, Ana?s,Augros, David,Panossian, Armen,Choppin, Sabine,Chessé, Matthieu,Colobert, Fran?oise,Leroux, Frédéric R.
-
supporting information
p. 725 - 732
(2017/01/18)
-
- Practical and metal-free electrophilic aromatic halogenation by interhalogen compounds generated in situ from N-halosuccinimide and catalytic TMSCL
-
Halomonochloride compounds (ClCl, BrCl, ICl) generated in situ from N-halosuccinimide and catalytic chlorotrimethylsilane (TMSCl, 0.1 equiv) can efficiently halogenate aromatic compounds to give halogenated products in good to excellent yields and selectivities. The reaction can be carried out at room temperature or at lower temperatures, requires only one hour, is practical to apply to a wide range of substrates, and provides a simple access to a variety of haloarene compounds. Georg Thieme Verlag Stuttgart New York.
- Maibunkaew, Tapanee,Thongsornkleeb, Charnsak,Tummatorn, Jumreang,Bunrit, Anon,Ruchirawat, Somsak
-
supporting information
p. 1769 - 1775
(2014/08/05)
-
- Pd-catalyzed direct arylation approach to the 6H-dibenzo[c,h]chromenes: Total synthesis of arnottin I
-
An efficient synthesis of 6H-dibenzo[c,h]chromenes has been achieved from 2-bromobenzyl-α-naphthyl ethers via a Pd-catalyzed Intramolecular direct-arylation using easily available Pd(PPh3)4 or Pd(OAc)2/PPh3 at elevated temperature. The reaction affords biaryl-coupling products in good to excellent yields in 6-9 h (up to 94% yields). A tentative mechanism has been proposed to understand the reaction pathway. Applying the methodology, a straightforward and concise total synthesis of arnottin I has been demonstrated by converting the biaryl-coupling products to the 6H-benzo[d]naphtho[1,2-b]pyran-6-one using pyridinium chlorochromate (PCC) mediated oxidation.
- De, Subhadip,Chaudhuri, Saikat,Mishra, Sourabh,Mamtani, Himanshu,Bisai, Alakesh
-
p. 1871 - 1884
(2014/01/17)
-
- Concise enantioselective total syntheses of (+)-homochelidonine, (+)-chelamidine, (+)-chelidonine, (+)-chelamine and (+)-norchelidonine by a PdII-catalyzed ring-opening strategy
-
New enantioselective syntheses of the B/C hexahydrobenzo[c]phenanthridine alkaloids (+)-homochelidonine, (+)-chelamidine, (+)-chelidonine, (+)-chelamine, and (+)-norchelidonine are described. Our rapid and convergent route to this class of natural products involved the development and application of a Pd II-catalyzed asymmetric ring-opening reaction of a mesoazabicyclic alkene with an aryl boronic acid as the key step. By screening a variety of functionalized ortho-substituted aryl boronic acids, chiral ligands and reaction conditions we were able to prepare the requisite cis-1-amino-2- aryldihydronaphthalenes in high yield and in up to 90% ee. Early attempts to complete the synthesis of (+)-homochelidonine using an N-Boc azabicyclic alkene are described in full. The successful route required a protecting group alteration followed by B ring for-mation and then stereoselective installation of the C-11 syn-hydroxy group by regioselective epoxide ring-opening using a hydride source. Ring-opening of the same epoxide intermediate with water ultimately led to the synthesis of (+)-chelamidine. The same strategy was then used to synthesize the other structurally similar B/C hexahydrobenzo[c] phenanthridine alkaloids, (+)-chelidonine, (+)-chelamidine, and (+)norchelidonine.
- Fleming, Matthew J.,McManus, Helen A.,Rudolph, Alena,Chan, Walter H.,Ruiz, Jeremy,Dockendorff, Chris,Lautens, Mark
-
body text
p. 2112 - 2124
(2009/04/06)
-
- Enantioselective total synthesis of (+)-homochelidonine by a Pd II-catalyzed asymmetric ring-opening reaction of a meso-azabicyclic alkene with an aryl boronic acid
-
(Chemical Equation Presented) An efficient and highly convergent enantioselective synthesis of (+)-homochelidonine has been achieved (see scheme; Cbz = benzyloxycarbonyl, MOM = methoxymethyl) and relied on a new and powerful desymmetrizing ring-opening reaction of a meso-azabicycle with an aryl boronic acid. The route should allow access to other hexahydrobenzo[c]phenanthridine alkaloids.
- McManus, Helen A.,Fleming, Matthew J.,Lautens, Mark
-
p. 433 - 436
(2008/02/02)
-
