- Twofold C?H Activation Enables Synthesis of a Diazacoronene-Type Fluorophore with Near Infrared Emission Through Isosteric Replacement
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The synthesis and photophysical properties of a soluble amide-embedded coronene is reported. The key step in this synthesis is the twofold C?H activation of diazaperylene by a rhodium(III)Cp* catalyst. This unprecedented structural motif shows intense fluorescence in the near infrared region with a small Stokes shift and a distinct vibronic structure, which exhibits a slight extent of negative solvatochromism. Comparison of this compound with some relevant compounds revealed the importance of the amide incorporation in the peripheral concave region including an angular position to retain high aromaticity reflecting that of parent coronene. Treatment of this compound with Lewis acid B(C6F5)3 formed a bis-adduct, which exhibited enhanced aromaticity as a consequence of the increased double bond character of the amide C?N bonds.
- Gre?ies, Steffen,Ito, Masato,Sakai, Mika,Osaki, Hiroshi,Kim, Ju Hyun,Gensch, Tobias,Daniliuc, Constantin,Ando, Naoki,Yamaguchi, Shigehiro,Glorius, Frank
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- Electrochemical control of single-molecule conductance by fermi-level tuning and conjugation switching
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Controlling charge transport through a single molecule connected to metallic electrodes remains one of the most fundamental challenges of nanoelectronics. Here we use electrochemical gating to reversibly tune the conductance of two different organic molecules, both containing anthraquinone (AQ) centers, over >1 order of magnitude. For electrode potentials outside the redox-active region, the effect of the gate is simply to shift the molecular energy levels relative to the metal Fermi level. At the redox potential, the conductance changes abruptly as the AQ unit is oxidized/reduced with an accompanying change in the conjugation pattern between linear and cross conjugation. The most significant change in conductance is observed when the electron pathway connecting the two electrodes is via the AQ unit. This is consistent with the expected occurrence of destructive quantum interference in that case. The experimental results are supported by an excellent agreement with ab initio transport calculations.
- Baghernejad, Masoud,Zhao, Xiaotao,Barul rnso, Kristian,Füeg, Michael,Moreno-Garca, Pavel,Rudnev, Alexander V.,Kaliginedi, Veerabhadrarao,Vesztergom, Soma,Huang, Cancan,Hong, Wenjing,Broekmann, Peter,Wandlowski, Thomas,Thygesen, Kristian S.,Bryce, Martin R.
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- Zinc-Ion-Stabilized Charge-Transfer Interactions Drive Self-Complementary or Complementary Molecular Recognition
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Here, we show that charge-transfer interactions determine whether donor and acceptor ditopic ligands will associate in a complementary or self-complementary fashion upon metal-ion clipping. Anthracene-based (9,10LD and 1,5LD) and anthraquinone-based (1,5LA) ditopic ligands containing two imidazole side arms as zinc coordination sites were designed. The 9,10LD and 1,5LA systems associated in a complementary fashion (LA/LD/LA) upon clipping by two zinc ions (Zn2+) to form an alternating donor-acceptor assembly [(9,10LD)(1,5LA)2-(Zn2+)2]. However, once the charge-transfer interactions were perturbed by subtle modifications of the imidazole side arms (9,10LD′(S) and 1,5LA′(S)), self-complementary association (LD′/LD′/LD′/LD′ and LA′/LA′/LA′/LA′) between the donor (9,10LD′(S)) and acceptor (1,5LA′(S)) ligands predominantly occurred to form homoassemblies [(9,10LD′(S))4-(Zn2+)2 and (1,5LA′(S))4-(Zn2+)2]. As in the case of a homochiral pair (9,10LD′(S) and 1,5LA′(S)), self-complementary association (narcissistic self-sorting) occurred in the Zn2+ assembly with heterochiral combinations of the donor and acceptor ligands (9,10LD′(S)/1,5LA′(R) and 9,10LD′(S)/1,5LA′(R)/1,5LA′(R)). Narcissistic self-sorting also took place between the positional isomer of the donor ligands (9,10LD and 1,5LD) to form individual homoligand assemblies [(9,10LD)4-(Zn2+)2 and (1,5LD)4-(Zn2+)2]. Conversely, statistical association took place in the Zn2L4 assembly process of an isomorphous pair of the donor and acceptor ligands (1,5LD and 1,5LA).
- Iseki, Shuta,Kishida, Sakura,Nonomura, Kohei,Ogata, Daiji,Yuasa, Junpei
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supporting information
p. 15842 - 15851
(2020/10/18)
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- Synthesis and properties of sterically crowded triarylphosphines bearing anthra- and naphtho-quinones, and their oligomers
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Sterically crowded triarylphosphines bearing anthraquinones were synthesized by SuzukieMiyaura coupling of arylboronic acids derived from (bromoaryl)phosphines with haloanthraquinones. The anthraquinone bearing the two triarylphosphine moieties at the 2,6
- Sasaki, Shigeru,Ogawa, Kazunobu,Nakamura, Kazuhiro,Yoshifuji, Masaaki,Morita, Noboru
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supporting information
p. 525 - 533
(2014/03/21)
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- Intramolecular behaviors of anthryldicarbenic systems: Dibenzo[b,f]pentalene and, 1H,5H-dicyclobuta[de,kl]anthracene
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9,10-Bis[methoxy(trimethylsilyl)methyl]anthracenes (24), synthesized from 9,10-dilithioanthracene (26) and bromomethoxytrimethylsilylmethane (27, 2 equiv), decompose (550-650 °C/10-3 mmHg) carbenically to dibenzo[b,f]pentalene (28, >48%). 9,10-Anthryldicarbenes 39 or their equivalents convert to pentalene 28 rather than di-peri-cyclobutanthracenes 30 and 31, benzobiphenylene 32, or extended rearrangement products 33-38. Formation of 28 from 24 raises questions with respect to the behavior of 1,3,4,6-cycloheptatetraenyl-1-carbenes 49, 2,4,5,7-cyclooctatetraenylidene 51, 2,5,7-cyclooctatriene-1,4-diylidene 52, 1,2,4,5,7-cyclooctapentaene 53, and bicyclo[4.1.0]heptatrienyl-1-carbenes 54 and to carbon-skeleton and hydrogen rearrangements of anthryldicarbenes 39 and/or their equivalents at various temperatures. 1,5-Bis[methoxy(trimethylsilyl)methyl]anthracenes (25), prepared from 1,5-diiodoanthracene (63) and methoxytrimethylsilylmethylzinc bromide (57, 2 equiv) as catalyzed by PdCl2(PPh3)2, yield the di-peri-carbenic reaction product 1H,5H-dicyclobuta[de,kl]anthracene (30, >40%) on pyrolysis at 550-650 °C/10-3 mmHg. Proof of structure and various aspects of the mechanisms of formation of 30 are discussed.
- Kendall,Shechter
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p. 6643 - 6649
(2007/10/03)
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