Polymorphic Molecular Materials—The Importance of Tertiary Structures

Miller, Joel S.

doi:10.1002/(sici)1521-4095(199812)10:18<1553::aid-adma1553>3.0.co;2-i

Cited by 30 publications

(19 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The existence of polymorphic materials each exhibiting different magnetic behavior is frequently observed, and should be expected, in studies of molecule-based magnets (and superconductors etc.). 46 Solvated materials, sometimes erroneously called pseudo-polymorphs, are different materials with respect to the non-solvated form, and like polymorphs frequently exhibit different magnetic behaviors, and sometimes the magnetic properties are enhanced with respect to the non-solvated form(s). Likewise, different degrees of solvation may impart different magnetic behaviors.…”

Section: Isolated Neutral Radicalsmentioning

confidence: 99%

Magnetically ordered molecule-based materials

2011

Self Cite

View full text Add to dashboard Cite

Magnets composed of molecular components that provide both electron spins and spin-coupling pathways can stabilize bulk magnetic ordering. This was first reported for the ionic, zero-dimensional (0-D) electron transfer salt [Fe(C(5)Me(5))(2)](+)[TCNE]˙(-) (TCNE = tetracyanoethylene), which orders as a ferromagnet at T(c) = 4.8 K. Later V[TCNE](x) (x ∼ 2) was characterized to order above room temperature at 400 K (127 °C). Subsequently, numerous examples of organic- and molecule-based magnets have been characterized. In this critical review, after a discussion of the important aspects of magnetism pertaining to molecule-based magnets, including the determination of the magnetic ordering temperature (T(c)) these magnetically ordered materials are reviewed from a perspective of the structural dimensionality (208 references).

show abstract

Section: Isolated Neutral Radicalsmentioning

confidence: 99%

Magnetically ordered molecule-based materials

2011

Self Cite

View full text Add to dashboard Cite

show abstract

“…Polymorphism is a well studied phenomenon 21, 22 and is especially relevant in magnetism; it is anticipated that polymorphs of open-shell complexes would have different magnetic behaviour as such behaviour is inherently a solid-state supramolecular effect. 23 Polymorphism in molecule-based magnetic systems is observed less frequently, 24 although the celebrated case of p-NO 2 -phenyl-nitronyl nitroxide (the first organic ferromagnet) occurs in no less than four crystal phases, of which the β alone is a bulk ferromagnet. 25 In the case presented here, both αand β-2 exhibit roughly the same type of packing arrangement: a 2-D sheet of ligand fragments in the ab plane with the P-Au-Cl group filling the space between the This series of interactions generates 1-D chains of t BuNO fragments within the ab plane that are effectively shielded from one another (Fig.…”

Section: Synthesis and Characterization Of Gold Phosphine-radical Com...mentioning

confidence: 99%

Ferromagnetic interactions and polymorphism in radical-substituted gold phosphine complexes

Leznoff¹,

Rancurel²,

Sutter³

et al. 1999

J. Chem. Soc., Dalton Trans.

View full text Add to dashboard Cite

A series of gold() complexes containing aminoxyl radical-substituted phosphine ligands has been prepared. Complexes chloro{2-[(p-diphenylphosphino)phenyl]-4,4,5,5-tetramethylimidazoline 1-oxyl 3-oxide}gold and [tertbutyl(p-diphenylphosphinophenyl)aminoxyl]chlorogold were prepared by reaction of the free radical phosphine with AuClؒTHT (THT = tetrahydrothiophene) or by complexation of the radical precursor of the ligands to AuClؒTHT followed by oxidation of the resulting gold complex. The first complex forms two distinct polymorphic crystal phases: in CH 2 Cl 2 -Et 2 O 2 crystallizes as green plates (α) in the triclinic space group P1 ¯ and in CH 2 Cl 2 -hexanes as blue prisms (β) in the monoclinic space group P2 1 /a. The crystal structures of both polymorphs and that of the complex 4 have been solved. The different solid-state arrangement of the molecules in the two polymorphic forms yields different magnetic behaviour; both exhibit intermolecular antiferromagnetic interactions but α exhibits a maximum in χ m at 3.5 K while β shows no maximum. The favourable overlap of aminoxyl N-oxide groups in α causes this stronger interaction, which was modelled as a 1-D antiferromagnetic Heisenberg chain to give J = Ϫ3.2 cm Ϫ1 . The magnetic behaviour of the complex 4 was investigated down to 50 mK, showing dominant intermolecular ferromagnetic interactions but long range antiferromagnetic ordering at very low temperatures.

show abstract

“…The mechanisms by which porphyrins self-assemble on surfaces is complicated and is an area of active investigation [ 2 – 6 ]. The dynamics and advantages of supramolecular compounds of porphyrins within devices and in fabricated materials are relevant for molecular studies [ 7 – 8 ]. Properties of supramolecular films with porphyrins can be investigated with approaches such as non-linear optics [ 9 ], catalysis [ 10 ] and electronic measurements [ 11 – 13 ].…”

Section: Introductionmentioning

confidence: 99%

Heterostuctures of 4-(chloromethyl)phenyltrichlorosilane and 5,10,15,20-tetra(4-pyridyl)-21H,23H-porphine prepared on Si(111) using particle lithography: Nanoscale characterization of the main steps of nanopatterning

Chambers¹,

Garno²

2018

Beilstein J. Nanotechnol.

View full text Add to dashboard Cite

Nanostructures of 4-(chloromethyl)phenyltrichlorosilane (CMPS) were used as a foundation to attach and grow heterostructures of porphyrins and organosilanes. A protocol was developed with particle lithography using steps of immersion in organosilane solutions to selectively passivate the surface of Si(111) with octadecyltrichlorosilane (OTS). A methyl-terminated matrix was chosen to direct the growth of CMPS nanostructures to fill the uncovered sites of Si(111) to enable spatial confinement of the surface reaction. Silica spheres with a diameter of 500 nm were used as a surface mask to prepare nanoscopic holes within the OTS matrix film. Next, the samples were immersed in solutions of CMPS dissolved in toluene or bicyclohexane. Nanostructures of CMPS formed within the nanoholes, to furnish spatially selective sites for binding porphyrins. The samples were then characterized with AFM to evaluate the height and morphology of the CMPS nanostructures that had formed within the nanoholes of OTS. The samples were then refluxed in a porphyrin solution for selective binding to produce heterostructures. The attachment of porphyrins was evidenced by increases in the height and width of the CMPS nanopatterns. The measurements of size indicate that multiple layers of porphyrins were added. Through each step of the surface reaction the surrounding matrix of OTS showed minimal areas of nonspecific adsorption. The AFM studies provide insight into the mechanism of the self-polymerization of CMPS as a platform for constructing porphyrin heterostructures.

show abstract

Polymorphic Molecular Materials—The Importance of Tertiary Structures

Cited by 30 publications

References 9 publications

Magnetically ordered molecule-based materials

Magnetically ordered molecule-based materials

Ferromagnetic interactions and polymorphism in radical-substituted gold phosphine complexes

Heterostuctures of 4-(chloromethyl)phenyltrichlorosilane and 5,10,15,20-tetra(4-pyridyl)-21H,23H-porphine prepared on Si(111) using particle lithography: Nanoscale characterization of the main steps of nanopatterning

Contact Info

Product

Resources

About