Nucleobase-Functionalized 1,6-Dithiapyrene-Type Electron-Donors: Supramolecular Assemblies by Complementary Hydrogen-Bonds and π‑Stacks

Synthesis, crystal structures and redox properties of 1,6-dithiapyrene (DTPY)-type electron-donors functionalized with nucleobases (uracil, cytosine and adenine) were investigated. The electrochemical measurements showed that the uracil-substituted derivatives were slightly stronger electron-donors than DTPY, and the cytosine- and adenine-substitution caused a slight weakening of the electron-donating ability. In the crystal structures, DTPY-nucleobases constructed multidimensional assemblies by complementary hydrogen-bonds on the nucleobase moieties and π-stacks and S···S interactions on the DTPY skeleton. The uracil derivative formed two kinds of hydrogen-bonded pairs with different H-bonding modes (Watson–Crick and reverse Watson–Crick types), both of which were further linked through π-stacks on the DTPY skeleton to construct one-dimensional alternating columns. In the CH₂Cl₂ solvated crystal, the uracil derivative built up a two-dimensional π-layer by the complementary hydrogen-bonds and π-stacks. In the cytosine derivative, the complementary hydrogen-bonded pair assembled by the π-stacks and S···S interactions of the DTPY skeleton constructed a two-dimensional network. The adenine derivative formed a channel structure by the one-dimensional π-stack of complementary hydrogen-bonded pairs, where crystalline water molecules with a ladder-like hydrogen-bonded chain were included. Charge-transfer complexes of DTPY-nucleobases with tetracyanoquinodimethane possessed a neutral ground state and exhibited semiconductive behaviors with room temperature conductivities of 10^–6 to 10^–7 S cm^–1

Nucleobase-Functionalized 1,6-Dithiapyrene-Type Electron-Donors: Supramolecular Assemblies by Complementary Hydrogen-Bonds and π‑Stacks

Synthesis, crystal structures and redox properties of 1,6-dithiapyrene (DTPY)-type electron-donors functionalized with nucleobases (uracil, cytosine and adenine) were investigated. The electrochemical measurements showed that the uracil-substituted derivatives were slightly stronger electron-donors than DTPY, and the cytosine- and adenine-substitution caused a slight weakening of the electron-donating ability. In the crystal structures, DTPY-nucleobases constructed multidimensional assemblies by complementary hydrogen-bonds on the nucleobase moieties and π-stacks and S···S interactions on the DTPY skeleton. The uracil derivative formed two kinds of hydrogen-bonded pairs with different H-bonding modes (Watson–Crick and reverse Watson–Crick types), both of which were further linked through π-stacks on the DTPY skeleton to construct one-dimensional alternating columns. In the CH₂Cl₂ solvated crystal, the uracil derivative built up a two-dimensional π-layer by the complementary hydrogen-bonds and π-stacks. In the cytosine derivative, the complementary hydrogen-bonded pair assembled by the π-stacks and S···S interactions of the DTPY skeleton constructed a two-dimensional network. The adenine derivative formed a channel structure by the one-dimensional π-stack of complementary hydrogen-bonded pairs, where crystalline water molecules with a ladder-like hydrogen-bonded chain were included. Charge-transfer complexes of DTPY-nucleobases with tetracyanoquinodimethane possessed a neutral ground state and exhibited semiconductive behaviors with room temperature conductivities of 10^–6 to 10^–7 S cm^–1

Nucleobase-Functionalized 1,6-Dithiapyrene-Type Electron-Donors: Supramolecular Assemblies by Complementary Hydrogen-Bonds and π‑Stacks

Synthesis, crystal structures and redox properties of 1,6-dithiapyrene (DTPY)-type electron-donors functionalized with nucleobases (uracil, cytosine and adenine) were investigated. The electrochemical measurements showed that the uracil-substituted derivatives were slightly stronger electron-donors than DTPY, and the cytosine- and adenine-substitution caused a slight weakening of the electron-donating ability. In the crystal structures, DTPY-nucleobases constructed multidimensional assemblies by complementary hydrogen-bonds on the nucleobase moieties and π-stacks and S···S interactions on the DTPY skeleton. The uracil derivative formed two kinds of hydrogen-bonded pairs with different H-bonding modes (Watson–Crick and reverse Watson–Crick types), both of which were further linked through π-stacks on the DTPY skeleton to construct one-dimensional alternating columns. In the CH₂Cl₂ solvated crystal, the uracil derivative built up a two-dimensional π-layer by the complementary hydrogen-bonds and π-stacks. In the cytosine derivative, the complementary hydrogen-bonded pair assembled by the π-stacks and S···S interactions of the DTPY skeleton constructed a two-dimensional network. The adenine derivative formed a channel structure by the one-dimensional π-stack of complementary hydrogen-bonded pairs, where crystalline water molecules with a ladder-like hydrogen-bonded chain were included. Charge-transfer complexes of DTPY-nucleobases with tetracyanoquinodimethane possessed a neutral ground state and exhibited semiconductive behaviors with room temperature conductivities of 10^–6 to 10^–7 S cm^–1

Nucleobase-Functionalized 1,6-Dithiapyrene-Type Electron-Donors: Supramolecular Assemblies by Complementary Hydrogen-Bonds and π‑Stacks

Synthesis, crystal structures and redox properties of 1,6-dithiapyrene (DTPY)-type electron-donors functionalized with nucleobases (uracil, cytosine and adenine) were investigated. The electrochemical measurements showed that the uracil-substituted derivatives were slightly stronger electron-donors than DTPY, and the cytosine- and adenine-substitution caused a slight weakening of the electron-donating ability. In the crystal structures, DTPY-nucleobases constructed multidimensional assemblies by complementary hydrogen-bonds on the nucleobase moieties and π-stacks and S···S interactions on the DTPY skeleton. The uracil derivative formed two kinds of hydrogen-bonded pairs with different H-bonding modes (Watson–Crick and reverse Watson–Crick types), both of which were further linked through π-stacks on the DTPY skeleton to construct one-dimensional alternating columns. In the CH₂Cl₂ solvated crystal, the uracil derivative built up a two-dimensional π-layer by the complementary hydrogen-bonds and π-stacks. In the cytosine derivative, the complementary hydrogen-bonded pair assembled by the π-stacks and S···S interactions of the DTPY skeleton constructed a two-dimensional network. The adenine derivative formed a channel structure by the one-dimensional π-stack of complementary hydrogen-bonded pairs, where crystalline water molecules with a ladder-like hydrogen-bonded chain were included. Charge-transfer complexes of DTPY-nucleobases with tetracyanoquinodimethane possessed a neutral ground state and exhibited semiconductive behaviors with room temperature conductivities of 10^–6 to 10^–7 S cm^–1

Nucleobase-Functionalized 1,6-Dithiapyrene-Type Electron-Donors: Supramolecular Assemblies by Complementary Hydrogen-Bonds and π‑Stacks

Synthesis, crystal structures and redox properties of 1,6-dithiapyrene (DTPY)-type electron-donors functionalized with nucleobases (uracil, cytosine and adenine) were investigated. The electrochemical measurements showed that the uracil-substituted derivatives were slightly stronger electron-donors than DTPY, and the cytosine- and adenine-substitution caused a slight weakening of the electron-donating ability. In the crystal structures, DTPY-nucleobases constructed multidimensional assemblies by complementary hydrogen-bonds on the nucleobase moieties and π-stacks and S···S interactions on the DTPY skeleton. The uracil derivative formed two kinds of hydrogen-bonded pairs with different H-bonding modes (Watson–Crick and reverse Watson–Crick types), both of which were further linked through π-stacks on the DTPY skeleton to construct one-dimensional alternating columns. In the CH₂Cl₂ solvated crystal, the uracil derivative built up a two-dimensional π-layer by the complementary hydrogen-bonds and π-stacks. In the cytosine derivative, the complementary hydrogen-bonded pair assembled by the π-stacks and S···S interactions of the DTPY skeleton constructed a two-dimensional network. The adenine derivative formed a channel structure by the one-dimensional π-stack of complementary hydrogen-bonded pairs, where crystalline water molecules with a ladder-like hydrogen-bonded chain were included. Charge-transfer complexes of DTPY-nucleobases with tetracyanoquinodimethane possessed a neutral ground state and exhibited semiconductive behaviors with room temperature conductivities of 10^–6 to 10^–7 S cm^–1

Intermolecular Hydrogen-Bond Networks and Physical Properties of BF₄^– and TCNQ^{<b>•</b>–} Salts of Three-Fold Symmetric Tris(alkylamino)phenalenyliums

Synthesis, redox properties, and crystal structures of tris­(alkylamino)­phenalenyliums (TAP) having alkyl groups (<i>n</i>-Pr, <i>i</i>-Pr, <i>t</i>-Bu) and their charge-transfer salts with tetracyanoquinodimethane radical anion (TCNQ^{<b>•</b>–}) were investigated. The electrochemical measurements revealed that TAP exhibits two irreversible reduction processes to neutral radical and anion species. The introduction of an alkylamino group caused a large negative shift of the first reduction potential and a significant decrease of the on-site Coulomb repulsion because of the electron-donating nature of amino groups and the extension of the π-electronic system. In the crystal structures of the BF₄^– salts, the TAP skeleton possesses a nearly 3-fold symmetric molecular plane indicating the delocalization of positive charge. The face-to-face stack of TAP formed π-dimer or columnar structures, which were connected through intermolecular N–H···F hydrogen bonds with BF₄^– to construct multidimensional network structures. The TCNQ^{<b>•</b>–} salts prepared by the metathesis method were characterized as fully ionic salts with a 1:1 component ratio. In the crystal structures, both TAP and TCNQ^{<b>•</b>–} molecules formed π-dimers, and the intermolecular hydrogen bonds between TAP and TCNQ^{<b>•</b>–} constructed a two-dimensional sheet

Intermolecular Hydrogen-Bond Networks and Physical Properties of BF₄^– and TCNQ^{<b>•</b>–} Salts of Three-Fold Symmetric Tris(alkylamino)phenalenyliums

Synthesis, redox properties, and crystal structures of tris­(alkylamino)­phenalenyliums (TAP) having alkyl groups (<i>n</i>-Pr, <i>i</i>-Pr, <i>t</i>-Bu) and their charge-transfer salts with tetracyanoquinodimethane radical anion (TCNQ^{<b>•</b>–}) were investigated. The electrochemical measurements revealed that TAP exhibits two irreversible reduction processes to neutral radical and anion species. The introduction of an alkylamino group caused a large negative shift of the first reduction potential and a significant decrease of the on-site Coulomb repulsion because of the electron-donating nature of amino groups and the extension of the π-electronic system. In the crystal structures of the BF₄^– salts, the TAP skeleton possesses a nearly 3-fold symmetric molecular plane indicating the delocalization of positive charge. The face-to-face stack of TAP formed π-dimer or columnar structures, which were connected through intermolecular N–H···F hydrogen bonds with BF₄^– to construct multidimensional network structures. The TCNQ^{<b>•</b>–} salts prepared by the metathesis method were characterized as fully ionic salts with a 1:1 component ratio. In the crystal structures, both TAP and TCNQ^{<b>•</b>–} molecules formed π-dimers, and the intermolecular hydrogen bonds between TAP and TCNQ^{<b>•</b>–} constructed a two-dimensional sheet

Selective Formation of Conductive Network by Radical-Induced Oxidation

Cd-based coordination networks having channels were formed selectively by using a redox-active aromatic ligand 2,5,8-tri­(4-pyridyl)­1,3-diazaphenalene (TPDAP, <b>H</b>^<b>+</b><b>1</b>^<b>–</b>). An electron-conductive network having a π–π stacking columnar structure of TPDAP formed in the presence of a trace amount of TPDAP radical (<b>1</b>^•). In contrast, a nonconductive network having a dimer unit of <b>H</b>^<b>+</b><b>1</b>^<b>–</b> formed in the absence of <b>1</b>^•. These results suggest the presence of a unique oxidation mechanism of TPDAP induced by formation of <b>H</b>^<b>+</b><b>1</b>^<b>–</b><b>-1</b>^• dimer, which was initiated by a trace amount of <b>1</b>^•. The dimerization increased HOMO level of <b>H</b>^<b>+</b><b>1</b>^<b>–</b> moiety within the dimer to generate further radicals that could not form when <b>H</b>^<b>+</b><b>1</b>^<b>–</b> was well isolated in CH₃OH

Selective Formation of Conductive Network by Radical-Induced Oxidation

Cd-based coordination networks having channels were formed selectively by using a redox-active aromatic ligand 2,5,8-tri­(4-pyridyl)­1,3-diazaphenalene (TPDAP, <b>H</b>^<b>+</b><b>1</b>^<b>–</b>). An electron-conductive network having a π–π stacking columnar structure of TPDAP formed in the presence of a trace amount of TPDAP radical (<b>1</b>^•). In contrast, a nonconductive network having a dimer unit of <b>H</b>^<b>+</b><b>1</b>^<b>–</b> formed in the absence of <b>1</b>^•. These results suggest the presence of a unique oxidation mechanism of TPDAP induced by formation of <b>H</b>^<b>+</b><b>1</b>^<b>–</b><b>-1</b>^• dimer, which was initiated by a trace amount of <b>1</b>^•. The dimerization increased HOMO level of <b>H</b>^<b>+</b><b>1</b>^<b>–</b> moiety within the dimer to generate further radicals that could not form when <b>H</b>^<b>+</b><b>1</b>^<b>–</b> was well isolated in CH₃OH

ESR and ¹H-,¹⁹F-ENDOR/TRIPLE Study of Fluorinated Diphenylnitroxides as Synthetic Bus Spin-Qubit Radicals with Client Qubits in Solution

Electron and nuclear spins as quantum bits (qubits) have been the focus of current issues in quantum information science/technology and related fields. From the viewpoint of chemistry, synthetic spin qubits are emerging. Diphenylnitroxide (DPNO) and its novel fluorine-substituted radicals are characterized as synthetic electron bus spin-qubits by continuous-wave ESR and ¹H-,¹⁹F-ENDOR/TRIPLE spectroscopy in solution and by DFT calculations. The partially fluorinated DPNOs have been synthesized to illustrate that they are candidates for the synthetic bus spin-qubits with well-defined client qubits. The fluorinated DPNOs undergo spin delocalization, dominating the robust spin polarization in the π-conjugation of phenyl rings, serving to increase the number of distinguishable client qubits from three to six