- Programmable Triboelectric Nanogenerators Dependent on the Secondary Building Units in Cadmium Coordination Polymers
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Precisely controlling the coordination microenvironment and electronic features of polynuclear secondary building units (SBUs) in coordination polymers (CPs) is an efficient approach to governing their fundamental performance. Here, different multinuclear
- Huang, Chao,Lu, Guizhen,Zhang, Yingying,Zhu, Kaifang,Cui, Siwen,Chen, Weihua,Wu, Zijie,Qiu, Mei,Mi, Liwei
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- Conformational locking by design: Relating strain energy with luminescence and stability in rigid metal-organic frameworks
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Minimization of the torsional barrier for phenyl ring flipping in a metal-organic framework (MOF) based on the new ethynyl-extended octacarboxylate ligand H8TDPEPE leads to a fluorescent material with a near-dark state. Immobilization of the ligand in the rigid structure also unexpectedly causes significant strain. We used DFT calculations to estimate the ligand strain energies in our and all other topologically related materials and correlated these with empirical structural descriptors to derive general rules for trapping molecules in high-energy conformations within MOFs. These studies portend possible applications of MOFs for studying fundamental concepts related to conformational locking and its effects on molecular reactivity and chromophore photophysics.
- Shustova, Natalia B.,Cozzolino, Anthony F.,Dincǎ, Mircea
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supporting information
p. 19596 - 19599
(2013/02/22)
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- Dendritic structure having a potential gradient: New synthesis and properties of carbazole dendrimers
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A new synthetic route for carbazole dendrimers was discovered using the copper-catalyzed N-arylation reaction. This synthetic route allowed synthesizing the fourth generation carbazole dendrimer and several derivatives for the first time. The crystal structure, Mark-Houwink-Sakurada plots, and UV-vis and fluorescence studies showed that the dendritic carbazole backbone has a rigid and highly twisted structure. From the measurement of the redox potential of the ferrocene derivatives, the IR spectra of the benzophenone derivatives, and complexation behavior of the phenylazomethine derivatives, the inductive electron-withdrawing effect of the carbazole dendron was revealed. This suggested that the summation of this electron withdrawal from each layer may produce a potential gradient such that the outer layer is electron-rich and the inner layer is electron-poor in the carbazole dendron. By assignment of the 1H and 13C NMR spectra of the dendron, the existence of this kind ofpotential gradient was proved. Overall, these data show the ?-polari zation substituent effect of the carbazole unit, and their summation determines the potential gradient in the repeating dendritic structure of the carbazole dendrimer.
- Albrecht, Ken,Yamamoto, Kimihisa
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supporting information; experimental part
p. 2244 - 2251
(2009/07/30)
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- Preparation of Complexing Compounds Containing Two 2,6-bis-4-ethynylpyridine Subunits
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Compounds containing two 2,6-bis-4-ethynylpyridine subunits have been prepared by coupling reactions between diiodoarenes and acetylenes in the presence of a palladium catalyst and copper(I) iodide.
- Takalo, Harri,Haenninen, Elina,Kankare, Jouko
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p. 662 - 665
(2007/10/02)
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- Inverse Triphenylmethylium Dyes
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When in the conventional triphenymethylium dye systems of the crystal violet and malachit green type, 6 and 7, the N-donor and C(+)-acceptor centers are interchanged, the "Inverse Triphenylmethylium Dye Types" 4 and 5 are obtained, showing very similar colors.The stable models with R = phenyl (8 - 10) and R = p-tolyl (11 - 13) were investigated in more detail.The visual observations were supported by the VIS spectra which showed nearly the same longest wavelength absorption maxima for corresponding pairs of inverse and conventional dye representatives.The experimental results can be interpreted with a simple HMO-model according to which the longest wavelength absorptions correspond here to transitions of equal energy from weakly bonding to nonbonding and from nonbonding to weakly antibonding molecular orbitals, respectively.On the same basis numerous isoelectronic variants of that dye type can be envisaged.In the NMR-spectra of the new dyes, characteristically increasing deshieldings of nearly all positions are observed in going from the mono- (10(+), 13(+)) through the di- (9(++), 12(++)) to the trications (8(+++), 11(+++)). - Key words: Dyes, Di-, Tricarbeniumions, NMR Spectra, VIS Spectra
- Hellwinkel, Dieter,Gaa, Heinrich Georg,Gottfried, Reiner
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p. 1045 - 1060
(2007/10/02)
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