Potential molecular materials based on organic-inorganic charge-transfer salts derived from [Mo6O19]2− isopolyoxoanion and hemicyanine dyes: Synthesis, spectra properties and X-ray structure

Improved Molecular Rectification from Self-Assembled Monolayers of a Sterically Hindered Dye

“…Intuitively, nonplanarity of the D−π−A + moiety should diminish with decreasing size of the substituent groups, and calculation of the dihedral angles between the planes of the component rings of the donor and acceptor moieties using the MOPAC/AM1 program of Cerius2 (Accelrys, Cambridge) provides confirmation. AM1 derived angles range from 61° for the sterically hindered dye ( 1a ) to 10° for the nonrectifying 4-[2-(4-dimethylaminophenyl)-vinyl]-pyridinium analogue ( 3 ), the almost planar structure of the latter also being confirmed by X-ray structural studies. ,

12 Molecular structures of self-assembling molecules that exhibit weaker steric hindrance as groups on opposite sides of the central CHCH bridge are progressively changed from double-ring to single-ring substituents. For clarity, the counterions are omitted.

…”

Improved Molecular Rectification from Self-Assembled Monolayers of a Sterically Hindered Dye

“…Intuitively, nonplanarity of the D−π−A + moiety should diminish with decreasing size of the substituent groups, and calculation of the dihedral angles between the planes of the component rings of the donor and acceptor moieties using the MOPAC/AM1 program of Cerius2 (Accelrys, Cambridge) provides confirmation. AM1 derived angles range from 61° for the sterically hindered dye ( 1a ) to 10° for the nonrectifying 4-[2-(4-dimethylaminophenyl)-vinyl]-pyridinium analogue ( 3 ), the almost planar structure of the latter also being confirmed by X-ray structural studies. ,

12 Molecular structures of self-assembling molecules that exhibit weaker steric hindrance as groups on opposite sides of the central CHCH bridge are progressively changed from double-ring to single-ring substituents. For clarity, the counterions are omitted.

…”

Polyoxometalate-Based Molecular Materials

“…With these ideas in mind, You et al investigated charge-transfer salts resulting from the combination of Lindqvist and α-Keggin-type anions with hemicyanine dyes which are known to have the largest SHG efficiency to date (1000 times of urea), and hexamethylphosphoramide which has a large dipole moment. The results indicate the presence of a definite (albeit weak) second-order optical response in the charge-transfer salt resulting from the reaction of the silicododecatungstate acid with the hexamethylphosphoramide base 72 which crystallizes in the noncentrosymmetric space group P 2 1 , while the combination of [Mo 6 O 19 ] 2- anion with hemicyanine dyes has revealed an absence of SHG due to centrosymmetry of the crystals . The highest second-order nonlinear optical response has been observed in the noncentrosymmetric charge-transfer complex [4-DMSP] 4 (NH 2 Me 2 ) 2 [HSiFeMo 11 O 40 ]·3H 2 O (4-DMSP = 4[ p -(dimethylamino)styryl]pyridine).…”

“…The results indicate the presence of a definite (albeit weak) second-order optical response in the charge-transfer salt resulting from the reaction of the silicododecatungstate acid with the hexamethylphosphoramide base 72 which crystallizes in the noncentrosymmetric space group P2 1 , while the combination of [Mo 6 O 19 ] 2anion with hemicyanine dyes has revealed an absence of SHG due to centrosymmetry of the crystals. 73 The highest second-order nonlinear optical response has been observed in the noncentrosymmetric charge-transfer complex [4-DMSP] 4 (NH 2 Me 2 ) 2 [HSiFeMo 11 O 40 ]‚3H 2 O (4-DMSP ) 4[p-(dimethylamino)styryl]pyridine). This compound exhibits SHG of 1064 nm radiation with an efficiency 1.2 times that of KH 2 PO 4 under the same conditions.…”

Photoelectron Spectroscopy of Free Polyoxoanions Mo6O192- and W6O192- in the Gas Phase

“…. The Lindqvist anions and their derivatives have been studied extensively in the condensed phase. − Both the M 6 O 19 2- anions have also been observed previously in the gas phase by electrospray ionization mass spectrometry. − However, despite the fact that most of the theoretical work has been performed on the isolated M 6 O 19 2- anions, the fundamental properties of these species in the gas phase have not been experimentally studied in any detail.

1 The octahedral structure of the Lindqvist polyoxoanions.

…”

Improved Molecular Rectification from Self-Assembled Monolayers of a Sterically Hindered Dye

“…Intuitively, nonplanarity of the D−π−A + moiety should diminish with decreasing size of the substituent groups, and calculation of the dihedral angles between the planes of the component rings of the donor and acceptor moieties using the MOPAC/AM1 program of Cerius2 (Accelrys, Cambridge) provides confirmation. AM1 derived angles range from 61° for the sterically hindered dye ( 1a ) to 10° for the nonrectifying 4-[2-(4-dimethylaminophenyl)-vinyl]-pyridinium analogue ( 3 ), the almost planar structure of the latter also being confirmed by X-ray structural studies. ,

12 Molecular structures of self-assembling molecules that exhibit weaker steric hindrance as groups on opposite sides of the central CHCH bridge are progressively changed from double-ring to single-ring substituents. For clarity, the counterions are omitted.

…”

Polyoxometalate-Based Molecular Materials

“…With these ideas in mind, You et al investigated charge-transfer salts resulting from the combination of Lindqvist and α-Keggin-type anions with hemicyanine dyes which are known to have the largest SHG efficiency to date (1000 times of urea), and hexamethylphosphoramide which has a large dipole moment. The results indicate the presence of a definite (albeit weak) second-order optical response in the charge-transfer salt resulting from the reaction of the silicododecatungstate acid with the hexamethylphosphoramide base 72 which crystallizes in the noncentrosymmetric space group P 2 1 , while the combination of [Mo 6 O 19 ] 2- anion with hemicyanine dyes has revealed an absence of SHG due to centrosymmetry of the crystals . The highest second-order nonlinear optical response has been observed in the noncentrosymmetric charge-transfer complex [4-DMSP] 4 (NH 2 Me 2 ) 2 [HSiFeMo 11 O 40 ]·3H 2 O (4-DMSP = 4[ p -(dimethylamino)styryl]pyridine).…”

“…The results indicate the presence of a definite (albeit weak) second-order optical response in the charge-transfer salt resulting from the reaction of the silicododecatungstate acid with the hexamethylphosphoramide base 72 which crystallizes in the noncentrosymmetric space group P2 1 , while the combination of [Mo 6 O 19 ] 2anion with hemicyanine dyes has revealed an absence of SHG due to centrosymmetry of the crystals. 73 The highest second-order nonlinear optical response has been observed in the noncentrosymmetric charge-transfer complex [4-DMSP] 4 (NH 2 Me 2 ) 2 [HSiFeMo 11 O 40 ]‚3H 2 O (4-DMSP ) 4[p-(dimethylamino)styryl]pyridine). This compound exhibits SHG of 1064 nm radiation with an efficiency 1.2 times that of KH 2 PO 4 under the same conditions.…”

Photoelectron Spectroscopy of Free Polyoxoanions Mo6O192- and W6O192- in the Gas Phase

“…. The Lindqvist anions and their derivatives have been studied extensively in the condensed phase. − Both the M 6 O 19 2- anions have also been observed previously in the gas phase by electrospray ionization mass spectrometry. − However, despite the fact that most of the theoretical work has been performed on the isolated M 6 O 19 2- anions, the fundamental properties of these species in the gas phase have not been experimentally studied in any detail.

1 The octahedral structure of the Lindqvist polyoxoanions.

…”

Improved Molecular Rectification from Self-Assembled Monolayers of a Sterically Hindered Dye

“…Intuitively, nonplanarity of the D−π−A + moiety should diminish with decreasing size of the substituent groups, and calculation of the dihedral angles between the planes of the component rings of the donor and acceptor moieties using the MOPAC/AM1 program of Cerius2 (Accelrys, Cambridge) provides confirmation. AM1 derived angles range from 61° for the sterically hindered dye ( 1a ) to 10° for the nonrectifying 4-[2-(4-dimethylaminophenyl)-vinyl]-pyridinium analogue ( 3 ), the almost planar structure of the latter also being confirmed by X-ray structural studies. ,

12 Molecular structures of self-assembling molecules that exhibit weaker steric hindrance as groups on opposite sides of the central CHCH bridge are progressively changed from double-ring to single-ring substituents. For clarity, the counterions are omitted.

…”

Polyoxometalate-Based Molecular Materials

“…With these ideas in mind, You et al investigated charge-transfer salts resulting from the combination of Lindqvist and α-Keggin-type anions with hemicyanine dyes which are known to have the largest SHG efficiency to date (1000 times of urea), and hexamethylphosphoramide which has a large dipole moment. The results indicate the presence of a definite (albeit weak) second-order optical response in the charge-transfer salt resulting from the reaction of the silicododecatungstate acid with the hexamethylphosphoramide base 72 which crystallizes in the noncentrosymmetric space group P 2 1 , while the combination of [Mo 6 O 19 ] 2- anion with hemicyanine dyes has revealed an absence of SHG due to centrosymmetry of the crystals . The highest second-order nonlinear optical response has been observed in the noncentrosymmetric charge-transfer complex [4-DMSP] 4 (NH 2 Me 2 ) 2 [HSiFeMo 11 O 40 ]·3H 2 O (4-DMSP = 4[ p -(dimethylamino)styryl]pyridine).…”

“…The results indicate the presence of a definite (albeit weak) second-order optical response in the charge-transfer salt resulting from the reaction of the silicododecatungstate acid with the hexamethylphosphoramide base 72 which crystallizes in the noncentrosymmetric space group P2 1 , while the combination of [Mo 6 O 19 ] 2anion with hemicyanine dyes has revealed an absence of SHG due to centrosymmetry of the crystals. 73 The highest second-order nonlinear optical response has been observed in the noncentrosymmetric charge-transfer complex [4-DMSP] 4 (NH 2 Me 2 ) 2 [HSiFeMo 11 O 40 ]‚3H 2 O (4-DMSP ) 4[p-(dimethylamino)styryl]pyridine). This compound exhibits SHG of 1064 nm radiation with an efficiency 1.2 times that of KH 2 PO 4 under the same conditions.…”

Photoelectron Spectroscopy of Free Polyoxoanions Mo6O192- and W6O192- in the Gas Phase

“…. The Lindqvist anions and their derivatives have been studied extensively in the condensed phase. − Both the M 6 O 19 2- anions have also been observed previously in the gas phase by electrospray ionization mass spectrometry. − However, despite the fact that most of the theoretical work has been performed on the isolated M 6 O 19 2- anions, the fundamental properties of these species in the gas phase have not been experimentally studied in any detail.

1 The octahedral structure of the Lindqvist polyoxoanions.

…”