TY  - JOUR
AU  - Lehmann, Matthias
AU  - Jahr, Michael
AU  - Donnio, Bertrand
AU  - Graf, Robert
AU  - Gemming, Sibylle
AU  - Popov, Igor
PY  - 2008
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/291
AB  - Star-shaped mesogens with a phloroglucinol or a trimesic acid core and oligobenzoate arms with up to five repeating units have been synthesised. non-conventional mesogens form various columnar mesophases over a broad temperature range. The liquid-crystal phases were characterised by optical microscopy, differential scanning calorimetry, X-ray diffraction, dilatometry and solid-state NMR spectroscopy. In addition to the high-temperature hexagonal columnar phases, the columnar self-assemblies undulate upon cooling and consequently form higher-ordered body-centred orthorhombic columnar 3D structures. A model of E-shaped folded conformers helically displaced along the columns is proposed. Helical preorganisation in the hexagonal phase precedes the transition to the low-temperature phases. Space filling and nano-segregation compete in the self-organisation process, thus aliphatic chains and the polar oligobenzoate scaffold are not perfectly separated in these star-shaped mesogens.
PB  - Wiley-V C H Verlag Gmbh, Weinheim
T2  - Chemistry-A European Journal
T1  - Star-shaped oligobenzoates: Non-conventional mesogens forming columnar helical mesophases
EP  - 3576
IS  - 12
SP  - 3562
VL  - 14
DO  - 10.1002/chem.200700922
ER  - 

@article{
author = "Lehmann, Matthias and Jahr, Michael and Donnio, Bertrand and Graf, Robert and Gemming, Sibylle and Popov, Igor",
year = "2008",
abstract = "Star-shaped mesogens with a phloroglucinol or a trimesic acid core and oligobenzoate arms with up to five repeating units have been synthesised. non-conventional mesogens form various columnar mesophases over a broad temperature range. The liquid-crystal phases were characterised by optical microscopy, differential scanning calorimetry, X-ray diffraction, dilatometry and solid-state NMR spectroscopy. In addition to the high-temperature hexagonal columnar phases, the columnar self-assemblies undulate upon cooling and consequently form higher-ordered body-centred orthorhombic columnar 3D structures. A model of E-shaped folded conformers helically displaced along the columns is proposed. Helical preorganisation in the hexagonal phase precedes the transition to the low-temperature phases. Space filling and nano-segregation compete in the self-organisation process, thus aliphatic chains and the polar oligobenzoate scaffold are not perfectly separated in these star-shaped mesogens.",
publisher = "Wiley-V C H Verlag Gmbh, Weinheim",
journal = "Chemistry-A European Journal",
title = "Star-shaped oligobenzoates: Non-conventional mesogens forming columnar helical mesophases",
pages = "3576-3562",
number = "12",
volume = "14",
doi = "10.1002/chem.200700922"
}

Lehmann, M., Jahr, M., Donnio, B., Graf, R., Gemming, S.,& Popov, I.. (2008). Star-shaped oligobenzoates: Non-conventional mesogens forming columnar helical mesophases. in Chemistry-A European Journal
Wiley-V C H Verlag Gmbh, Weinheim., 14(12), 3562-3576.
https://doi.org/10.1002/chem.200700922

Lehmann M, Jahr M, Donnio B, Graf R, Gemming S, Popov I. Star-shaped oligobenzoates: Non-conventional mesogens forming columnar helical mesophases. in Chemistry-A European Journal. 2008;14(12):3562-3576.
doi:10.1002/chem.200700922 .

Lehmann, Matthias, Jahr, Michael, Donnio, Bertrand, Graf, Robert, Gemming, Sibylle, Popov, Igor, "Star-shaped oligobenzoates: Non-conventional mesogens forming columnar helical mesophases" in Chemistry-A European Journal, 14, no. 12 (2008):3562-3576,
https://doi.org/10.1002/chem.200700922 . .

TY  - JOUR
AU  - Popov, Igor
AU  - Gemming, Sibylle
AU  - Okano, Shinya
AU  - Ranjan, Nitesh
AU  - Seifert, Gotthard
PY  - 2008
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/272
AB  - We investigate the structural, electronic, and transport properties of mechanically deformed Mo6S6 nanowires using a density-functional based tight binding method extended with a Green's functions formalism. We present two interesting results: first, the properties of the wire are not affected by bending, and second, a metal-insulator transition occurs when the wire is twisted. This indicates that molybdenum sulfide nanowires can be used as a nanocable to flexibly transfer information between electromechanical switches, which can be also constructed from the same wires. Hence, our results suggest the Mo6S6 nanowires as unique building blocks for future nanodevices.
PB  - Amer Chemical Soc, Washington
T2  - Nano Letters
T1  - Electromechanical Switch Based on Mo6S6 Nanowires
EP  - 4097
IS  - 12
SP  - 4093
VL  - 8
DO  - 10.1021/nl801456f
ER  - 

@article{
author = "Popov, Igor and Gemming, Sibylle and Okano, Shinya and Ranjan, Nitesh and Seifert, Gotthard",
year = "2008",
abstract = "We investigate the structural, electronic, and transport properties of mechanically deformed Mo6S6 nanowires using a density-functional based tight binding method extended with a Green's functions formalism. We present two interesting results: first, the properties of the wire are not affected by bending, and second, a metal-insulator transition occurs when the wire is twisted. This indicates that molybdenum sulfide nanowires can be used as a nanocable to flexibly transfer information between electromechanical switches, which can be also constructed from the same wires. Hence, our results suggest the Mo6S6 nanowires as unique building blocks for future nanodevices.",
publisher = "Amer Chemical Soc, Washington",
journal = "Nano Letters",
title = "Electromechanical Switch Based on Mo6S6 Nanowires",
pages = "4097-4093",
number = "12",
volume = "8",
doi = "10.1021/nl801456f"
}

Popov, I., Gemming, S., Okano, S., Ranjan, N.,& Seifert, G.. (2008). Electromechanical Switch Based on Mo6S6 Nanowires. in Nano Letters
Amer Chemical Soc, Washington., 8(12), 4093-4097.
https://doi.org/10.1021/nl801456f

Popov I, Gemming S, Okano S, Ranjan N, Seifert G. Electromechanical Switch Based on Mo6S6 Nanowires. in Nano Letters. 2008;8(12):4093-4097.
doi:10.1021/nl801456f .

Popov, Igor, Gemming, Sibylle, Okano, Shinya, Ranjan, Nitesh, Seifert, Gotthard, "Electromechanical Switch Based on Mo6S6 Nanowires" in Nano Letters, 8, no. 12 (2008):4093-4097,
https://doi.org/10.1021/nl801456f . .

TY  - JOUR
AU  - Gemming, Sibylle
AU  - Popov, Igor
AU  - Lehmann, Matthias
PY  - 2007
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/229
AB  - Star-shaped molecules, based on a phloroglucinol core with three oligobenzoate arms, are powerful mesogens that can be combined to columnar liquid crystalline materials and soft organic crystals. The structural properties of such modern materials exhibit polymorphism at two different length scales. On the molecular level, the mesogens are highly flexible molecules with a large variety of almost isoenergetic conformers of varying propensity towards regular stacking in the bulk phase. On the supramolecular level, polymorphic structures occur, which comprise different liquid crystalline phases with anisotropic columnar order and soft crystals with a more isotropic three-dimensional ordering. For the smallest mesogen, the present results are evidence that the two forms of polymorphism are linked. Columnar liquid crystals are formed from a low-symmetry, folded conformer, which already accounts for the nano-segregation of the planar aromatic centre and the flexible aliphatic chain parts of the mesogen, whereas the soft, more isotropic crystals are grown from the C-3-symmetric, star-shaped conformer of a derivative with shorter alkyl chains. Molecular dynamics simulations confirm the stability of each structure at room temperature.
PB  - Taylor & Francis Ltd, Abingdon
T2  - Philosophical Magazine Letters
T1  - Polymorphism in liquid crystals from star-shaped mesogens
EP  - 891
IS  - 11
SP  - 883
VL  - 87
DO  - 10.1080/09500830701537959
ER  - 

@article{
author = "Gemming, Sibylle and Popov, Igor and Lehmann, Matthias",
year = "2007",
abstract = "Star-shaped molecules, based on a phloroglucinol core with three oligobenzoate arms, are powerful mesogens that can be combined to columnar liquid crystalline materials and soft organic crystals. The structural properties of such modern materials exhibit polymorphism at two different length scales. On the molecular level, the mesogens are highly flexible molecules with a large variety of almost isoenergetic conformers of varying propensity towards regular stacking in the bulk phase. On the supramolecular level, polymorphic structures occur, which comprise different liquid crystalline phases with anisotropic columnar order and soft crystals with a more isotropic three-dimensional ordering. For the smallest mesogen, the present results are evidence that the two forms of polymorphism are linked. Columnar liquid crystals are formed from a low-symmetry, folded conformer, which already accounts for the nano-segregation of the planar aromatic centre and the flexible aliphatic chain parts of the mesogen, whereas the soft, more isotropic crystals are grown from the C-3-symmetric, star-shaped conformer of a derivative with shorter alkyl chains. Molecular dynamics simulations confirm the stability of each structure at room temperature.",
publisher = "Taylor & Francis Ltd, Abingdon",
journal = "Philosophical Magazine Letters",
title = "Polymorphism in liquid crystals from star-shaped mesogens",
pages = "891-883",
number = "11",
volume = "87",
doi = "10.1080/09500830701537959"
}

Gemming, S., Popov, I.,& Lehmann, M.. (2007). Polymorphism in liquid crystals from star-shaped mesogens. in Philosophical Magazine Letters
Taylor & Francis Ltd, Abingdon., 87(11), 883-891.
https://doi.org/10.1080/09500830701537959

Gemming S, Popov I, Lehmann M. Polymorphism in liquid crystals from star-shaped mesogens. in Philosophical Magazine Letters. 2007;87(11):883-891.
doi:10.1080/09500830701537959 .

Gemming, Sibylle, Popov, Igor, Lehmann, Matthias, "Polymorphism in liquid crystals from star-shaped mesogens" in Philosophical Magazine Letters, 87, no. 11 (2007):883-891,
https://doi.org/10.1080/09500830701537959 . .

TY  - JOUR
AU  - Popov, Igor
AU  - Kunze, T.
AU  - Gemming, Sibylle
AU  - Seifert, Gotthard
PY  - 2007
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/227
AB  - The preferred adsorption sites and the propensity for a self-organised growth of the molybdenum sulfide cluster Mo6S8 on the Au(111) surface are investigated by density-functional band-structure calculations with pseudopotentials and a plane wave basis set. The quasi-cubic cluster preferentially adsorbs via a face and remains structurally intact. It experiences a strong, mostly non-ionic attraction to the surface at several quasi-isoenergetic adsorption positions. A scan of the potential energy surface exhibits only small barriers between adjacent strong adsorption sites. Hence, the cluster may move in a potential well with degenerate local energy minima at room temperature. The analysis of the electronic structure reveals a negligible electron transfer and S-Au hybridised states, which indicate that the cluster-surface interaction is dominated by S-Au bonds, with minor contributions from the Mo atom in the surface vicinity. All results indicate that Mo6S8 clusters on the Au(111) surface can undergo a template-mediated self-assembly to an ordered inorganic monolayer, which is still redox active and may be employed as surface-active agent in the integration of noble metal and ionic or biological components within nano-devices. Therefore, a classical potential model was developed on the basis of the DFT data, which allows to study larger cluster assemblies on the Au(111).
PB  - Springer, New York
T2  - European Physical Journal D
T1  - Self-assembly of Mo6S (8) clusters on the Au(111) surface
EP  - 446
IS  - 3
SP  - 439
VL  - 45
DO  - 10.1140/epjd/e2007-00170-1
ER  - 

@article{
author = "Popov, Igor and Kunze, T. and Gemming, Sibylle and Seifert, Gotthard",
year = "2007",
abstract = "The preferred adsorption sites and the propensity for a self-organised growth of the molybdenum sulfide cluster Mo6S8 on the Au(111) surface are investigated by density-functional band-structure calculations with pseudopotentials and a plane wave basis set. The quasi-cubic cluster preferentially adsorbs via a face and remains structurally intact. It experiences a strong, mostly non-ionic attraction to the surface at several quasi-isoenergetic adsorption positions. A scan of the potential energy surface exhibits only small barriers between adjacent strong adsorption sites. Hence, the cluster may move in a potential well with degenerate local energy minima at room temperature. The analysis of the electronic structure reveals a negligible electron transfer and S-Au hybridised states, which indicate that the cluster-surface interaction is dominated by S-Au bonds, with minor contributions from the Mo atom in the surface vicinity. All results indicate that Mo6S8 clusters on the Au(111) surface can undergo a template-mediated self-assembly to an ordered inorganic monolayer, which is still redox active and may be employed as surface-active agent in the integration of noble metal and ionic or biological components within nano-devices. Therefore, a classical potential model was developed on the basis of the DFT data, which allows to study larger cluster assemblies on the Au(111).",
publisher = "Springer, New York",
journal = "European Physical Journal D",
title = "Self-assembly of Mo6S (8) clusters on the Au(111) surface",
pages = "446-439",
number = "3",
volume = "45",
doi = "10.1140/epjd/e2007-00170-1"
}

Popov, I., Kunze, T., Gemming, S.,& Seifert, G.. (2007). Self-assembly of Mo6S (8) clusters on the Au(111) surface. in European Physical Journal D
Springer, New York., 45(3), 439-446.
https://doi.org/10.1140/epjd/e2007-00170-1

Popov I, Kunze T, Gemming S, Seifert G. Self-assembly of Mo6S (8) clusters on the Au(111) surface. in European Physical Journal D. 2007;45(3):439-446.
doi:10.1140/epjd/e2007-00170-1 .

Popov, Igor, Kunze, T., Gemming, Sibylle, Seifert, Gotthard, "Self-assembly of Mo6S (8) clusters on the Au(111) surface" in European Physical Journal D, 45, no. 3 (2007):439-446,
https://doi.org/10.1140/epjd/e2007-00170-1 . .

TY  - JOUR
AU  - Popov, Igor
AU  - Gemming, Sibylle
AU  - Seifert, Gotthard
PY  - 2007
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/201
AB  - The stability and the change of the structural and electronic properties of the molybdenum sulfide cluster Mo6S8 upon adsorption on the Au(111) surface are investigated by density functional band-structure calculations with pseudopotentials and a plane-wave basis set. The nearly cubic cluster preferably adsorbs via a face and maintains its structural integrity. It experiences a strong, mostly nonionic attraction to the surface at several quasi-isoenergetic adsorption positions. The analysis of the electronic structure reveals a negligible electron transfer and S-Au hybridized states, which indicate that the cluster-surface interaction is dominated by S-Au bonds, with minor contributions from the Mo atom in the surface vicinity. All results indicate that Mo6S8 clusters on the Au(111) surface are still redox active and can be employed as surface-active agent in the integration of noble metal and ionic or biological components within nanodevices.
PB  - Amer Physical Soc, College Pk
T2  - Physical Review B
T1  - Structural and electronic properties of Mo6S8 clusters deposited on a Au(111) surface investigated with density functional theory
IS  - 24
VL  - 75
DO  - 10.1103/PhysRevB.75.245436
ER  - 

@article{
author = "Popov, Igor and Gemming, Sibylle and Seifert, Gotthard",
year = "2007",
abstract = "The stability and the change of the structural and electronic properties of the molybdenum sulfide cluster Mo6S8 upon adsorption on the Au(111) surface are investigated by density functional band-structure calculations with pseudopotentials and a plane-wave basis set. The nearly cubic cluster preferably adsorbs via a face and maintains its structural integrity. It experiences a strong, mostly nonionic attraction to the surface at several quasi-isoenergetic adsorption positions. The analysis of the electronic structure reveals a negligible electron transfer and S-Au hybridized states, which indicate that the cluster-surface interaction is dominated by S-Au bonds, with minor contributions from the Mo atom in the surface vicinity. All results indicate that Mo6S8 clusters on the Au(111) surface are still redox active and can be employed as surface-active agent in the integration of noble metal and ionic or biological components within nanodevices.",
publisher = "Amer Physical Soc, College Pk",
journal = "Physical Review B",
title = "Structural and electronic properties of Mo6S8 clusters deposited on a Au(111) surface investigated with density functional theory",
number = "24",
volume = "75",
doi = "10.1103/PhysRevB.75.245436"
}

Popov, I., Gemming, S.,& Seifert, G.. (2007). Structural and electronic properties of Mo6S8 clusters deposited on a Au(111) surface investigated with density functional theory. in Physical Review B
Amer Physical Soc, College Pk., 75(24).
https://doi.org/10.1103/PhysRevB.75.245436

Popov I, Gemming S, Seifert G. Structural and electronic properties of Mo6S8 clusters deposited on a Au(111) surface investigated with density functional theory. in Physical Review B. 2007;75(24).
doi:10.1103/PhysRevB.75.245436 .

Popov, Igor, Gemming, Sibylle, Seifert, Gotthard, "Structural and electronic properties of Mo6S8 clusters deposited on a Au(111) surface investigated with density functional theory" in Physical Review B, 75, no. 24 (2007),
https://doi.org/10.1103/PhysRevB.75.245436 . .