1,4,7,10-Tetraisoalkyltetracenes: Tuning of Solid-State Optical Properties and Fluorescence Quantum Yields by Peripheral Modulation

Correction for the calculated XANES spectra of 1,4,7,10-alkyltetracenes considering the total electron yield (TEY) efficiency of sp2- and sp3-carbon atoms

The calculated X-ray-absorption-near-edge-structure (XANES) spectra in the CK region of 1,4,7,10-alkyltetracenes, which are composed of both sp2-C atoms in the tetracene ring and sp3-C atoms in the alkyl-chains, can be corrected by considering the total electron yield (TEY) efficiency of sp3-C relative to sp2-C. In the correction, the previously measured TEY efficiency of k = 0.51 is applied to the calculated transition probabilities for sp3-C atoms. Then the calculated CK-XANES obtained from density functional theory (DFT) calculations can well reproduce the measured TEY-CK-XANES. Especially, the calculated π*/σ* peak intensity ratios are in good agreement with the measured ones. This suggests that a similar correction for the calculated XANES is necessary for compounds composed of multi-components with different TEY efficiencies.

Total electron yield (TEY) efficiency of sp2 and sp3 carbon atoms in the TEY-X-ray absorption near-edge structure (XANES) of 1,4,7,10-alkyltetracenes

X-ray absorption near-edge structure (XANES) in the CK region of 1,4,7,10-alkyltetracenes, which are composed of sp2-C atoms in the tetracene ring and sp3-C atoms in the alkyl-chains, are measured using the total electron yield (TEY) and theoretically analyzed by DFT calculations to quantitatively investigate the π* and σ* peak intensities in the TEY-CK-XANES. The calculated π*/σ* peak intensity ratios are well approximated by the linear functions passing through the origin as a function of the sp2-C fraction, which is expressed as sp2-C/(sp2-C + sp3-C). In contrast, the measured π*/σ* peak intensity ratios are well approximated by curve functions passing through the origin, considering the TEY efficiency between sp2-C and sp3-C. The approximated curve functions indicate that the TEY efficiency of sp3-C is lower than that of sp2-C even in molecules. This confirms that the TEY efficiency of sp2-C and sp3-C should be considered in quantitative discussions on the sp2-C and sp3-C fractions from TEY-CK-XANES of carbon materials.

Systematic arrangement control of functional organic molecules

Systematic and precise arrangement control of functional organic molecules without changing both their molecular and layered structure was established.

A new fluorophore displaying remarkable solvatofluorochromism and solid-state light emission, and serving as a turn-on fluorescent sensor for cyanide ions

A new fluorophore displays remarkable solvatofluorochromism, a CIEE effect, and an intense blue-green fluorescence in the presence of cyanide ions.

Synthesis and Investigation of the Effect of Substitution on the Structure, Physical Properties, and Electrochemical Properties of Anthracenodifuran Derivatives

A series of syn/anti mixtures of anthradifuran (ADF) and substituent compounds were systematically synthesized, and the effect of substitution at the 5,11-positions on the neutral and radical states of ADF was investigated. All compounds were measured and analyzed by absorption and fluorescence spectroscopy, cyclic voltammetry, electrochemical absorption spectroscopy, and DFT calculations. The absorption spectra of 5,11-substituent compounds in their neutral state were red-shifted. In addition, the substituted compounds exhibited increased thermal stability with respect to the parent 1a because of elongation of the π-conjugation and an increased steric hindrance effect due to the bulky ethynyl substituent groups. The cyclic voltammograms of all of the compounds exhibited irreversible reduction potentials and irreversible oxidation potentials, except in the case of (trimethylsilyl)silylethynyl-substituted ADF. When the materials were subjected to oxidation/reduction potentials, the radical cation and anion species were generated. The absorption spectra of the radical-cation species of the compounds exhibited similar characteristics and similar absorption ranges (550-1400 nm), whereas the spectra of the radical anion species were blue-shifted (550-850 nm) compared than that of the parent 1a(•-) (550-1100 nm). The DFT computation results suggested that the radical states of lowest energy transitions occurred primarily from π to π(SOMO) or from π(SOMO) to π*.

1,7-Diethyl-4,10-diisopropyl-tetra-cene

The mol-ecule of the title compound, C(28)H(32), is located on a crystallographic inversion center. The ethyl groups are essentially coplanar with the tetra-cene ring, making a torsion angle of -0.4 (4)°. The isopropyl groups adopt an asymmetric conformation with their terminal methyl groups positioned on opposite sides of the tetra-cene plane [the Me-C-C-C torsion angles are -22.5 (4) and 100.9 (3)°]. In the crystal, the mol-ecules adopt an arrangement without significant π-π inter-actions along the stacking direction (y axis).

1,4,5,8-Tetraisopropylanthracene

The mol­ecules of the title compound, C₂₆H₃₄, possess crystallographically imposed inversion symmetry. The anthracene ring system is planar within 0.038 (1) Å. The two methyl groups in each independent isopropyl group are oriented on either side of the anthracene plane. In the crystal structure, the mol­ecules adopt a herringbone-like arrangement without π–π stacking.