The spin crossover (SCO) phenomenon defines an elegant class of switchable materials that can show cooperative transitions when long-range elastic interactions are present. Such multistepped transitions, targeted both fundamentally and for expanded data storage applications, antagonistic (i.e., competing ferro- antiferro-elastic interactions) drive concerted lattice distortions. To this end, a new SCO framework scaffold, [FeII(bztrz)2(PdII(CN)4)]·n(guest) (bztrz =...

The porous coordination framework material, Fe(NCS)2(bped)2·3EtOH, SCOF-3(Et) (where bped is dl-1,2-bis(4'-pyridyl)-1,2-ethanediol), displays a spin-crossover (SCO) transition that has been stimulated both thermally and by light irradiation. one-step thermal SCO (70−180 K) sensitive to the presence of molecular guests, with more gradual (70−225 apparent following desorption ethanol molecules hydrogen bond spin centers. Additional intraframework hydrogen-bonding interactions stabilize vacant...

The electronic switching properties of the nanoporous spin crossover framework [Fe(NCS)2(bpbd)2]·x(guest), SCOF-2, can be rationally manipulated via sorption a range molecular guests (acetone, ethanol, methanol, propanol, 1-acetonitrile) into 1-D channels this material. Pronounced changes to are related directly steric and influence individual guests: degree lattice cooperativity, as reflected in abruptness transition presence hysteresis, is strongly influenced by cooperative host−guest...

The nanoporous metal-organic framework, Fe(bpe)2(NCS)2 x 3(acetone), SCOF-4(Ac) (where bpe is 1,2-bis(4'-pyridyl)ethane), displays a two-step spin crossover (SCO) transition (65-155 K) that sensitive to the presence of acetone guest molecules. Structural analyses have revealed structural phase transition, from tetragonal (P42(1)c) orthorhombic (P2(1)2(1)2), associated with defines checkerboard-like ordering sites at high-spin:low-spin plateau. reversible desorption species accompanied by...

Bottoms up! A discrete metallo-supramolecular nanoball (see picture), synthesized by using "bottom-up" methodologies, uniquely undergoes a solvent-sensitive, physically addressable electronic spin switching. The switching occurs thermal, light, or solvent perturbation, where importantly it can be switched "on" "off" green red laser irradiation, respectively.

Play ball! A family of discrete metallo-supramolecular nanoballs (see picture) containing different divalent metals is produced by self-assembly. These species have porous structures, similar to metal–organic frameworks. Stepwise desolvation results in bare metal sites which can be functionalized with organic molecules; the interball cavities show high affinity for hydrogen gas. Detailed facts importance specialist readers are published as "Supporting Information". Such documents...

Abstract Materials that display multiple stepped spin crossover (SCO) transitions with accompanying hysteresis present the opportunity for ternary, quaternary, and quinary electronic switching data storage but are rare in existence. Herein, we first report of a four‐step hysteretic SCO framework. Single‐crystal structure analysis porous 3D Hofmann‐like material showed long‐range ordering states: HS, HS 0.67 LS 0.33 , 0.5 LS. These detailed structural studies provide insight into how...

Ambient temperature spin crossover with wide hysteresis has been achieved in 2D Hofmann-type materials, where removal of guest molecules optimises ligand–ligand interactions, resulting increased cooperativity.

Influential guests: An abrupt spin-crossover transition is exhibited by a nanoporous framework material that consists of interpenetrated two-dimensional grids linked hydrogen-bonding interactions. Desorption guest molecules from the highly robust host lattice occurs single-crystal-to-single-crystal transformation and leads to subtle changes in structure properties. Supporting information for this article available on WWW under http://www.wiley-vch.de/contents/jc_2002/2007/z603977_s.pdf or...

Three analogous one dimensional (1D) polymeric iron(II) spin crossover (SCO) materials containing the new ligand 4,6-bis(2',2''-pyridyl)pyrazine (bdpp) have been comprehensively characterised magnetically (thermal and light-induced) structurally. Within this series are two polymorphs of formula [Fe(NCS)(2)(bdpp)], 1 2 a, which differ in that phase undergoes a full two-step SCO (T(1/2(1))=135 K T(1/2(2))=90 K) whereas remains high (HS) over all temperatures. The central distinction between...

Abstract Covalent post‐synthetic modification is a versatile method for gaining high‐level synthetic control over functionality within porous metal–organic frameworks and generating new materials not accessible through one‐step framework syntheses. Here we apply this topotactic approach to spin crossover show detailed comparison of the structures properties as‐synthesised covalently modified phases that reaction proceeds quantitatively by thermally activated single‐crystal‐to‐single‐crystal...

A rare four-step spin crossover transition has been attained in a two-dimensional Hofmann-type material through the presence of an array antagonistic host–host and host–guest interactions.

The abrupt and hysteretic two-step spin crossover in a new triazole-based 2-D Hofmann-type complex shows record breaking 120 K intermediate plateau (IP) region stabilized by negative cooperative interactions.

A dinuclear iron(II) complex containing the new pyridyl bridging ligand, 2,5-di(2',2''-dipyridylamino)pyridine (ddpp) has been synthesised and characterised by single-crystal X-ray diffraction, magnetic susceptibility Mössbauer spectral methods. This compound, [Fe(2)(ddpp)(2)(NCS)(4)]4 CH(2)Cl(2), undergoes a two-step full spin crossover. Structural analysis at each of three plateau temperatures revealed molecule with states HS-HS, HS-LS LS-LS (HS: high spin, LS: low spin) for two centres....

A series of iron(III) 1-D polymeric materials the general formula [Fe(III)(Schiff-base)(L)](BPh(4)).n(CH(3)OH) (Schiff base = N,N'-ethylenebis(salicylaldimine) (H(2)salen), N,N'-o-phenylenebis(salicylaldimine) (H(2)salophen) and N,N'-ethylenebis(acety1acetone)-2,2'-imine (H(2) acen); L bridging di-pyridyl or di-imidazole ligand, n 0-4) analogues therein, have been synthesised structurally magnetically characterised. In this series, a range structural motifs are observed including linear...

Five mononuclear spin crossover iron(II) bis-meridional ligand complexes of the general formula [Fe(L)2](X)2·solvent, have been synthesized, where X = BF4- or ClO4-; L 2-(1-pyridin-2-ylmethyl-1H-pyrazol-3-yl)-pyrazine (picpzpz) 2-(3-(2-pyridyl)pyrazol-1-ylmethyl)pyridine) (picpypz); solvent MeOH EtOH. The magnetic and structural consequences systematic variation meridional ligand, solvent, anion, including a desolvated species, investigated. complex [Fe(picpzpz)2](BF4)2·MeOH, 1·MeOH,...

Extensive research is currently being conducted into metal complexes that can selectively deliver cytotoxins to hypoxic regions in tumours. The development of pharmacologically suitable agents requires an understanding appropriate ligand–metal systems for chaperoning cytotoxins. In this study, cobalt with tripodal tren (tris-(2-aminoethyl)amine) and tpa (tris-(2-pyridylmethyl)amine) ligands were prepared ancillary hydroxamic acid, β-diketone catechol several parameters, including: pKa,...

The reaction of the polydentate N-donor ligands bmtz, H2bmtz, and bptz with various silver salts was investigated. New 1D coordination polymers [Ag2(bmtz) (ClO4)]ClO4 (1), [Ag(bmtz)]ClO4·MeCN (2), [{Ag(tcm)}2(H2bmtz)(MeCN)] (3) [Ag(bptz)(NO3)] (5), 2-D sheet structures, [{Ag(tcm)}2bmtz] (4), were synthesized. structures are built up through combination bonds, hydrogen bonding, Ag–π, π–π, anion–π interactions to generate new supramolecular architectures. structure protonated amine salt...

A new functionalized 1,2,4-triazole ligand, 4-[(E)-2-(5-methyl-2-thienyl)vinyl]-1,2,4-triazole (thiome), was prepared to assess the broad applicability of strategically producing multistep spin transitions in two-dimensional Hofmann-type materials type [FeIIPd(CN)4(R-1,2,4-trz)2]·nH2O (R-1,2,4-trz = a 4-functionalized ligand). variety structural and magnetic investigations on resultant framework material [FeIIPd(CN)4(thiome)2]·2H2O (A·2H2O) reveal that high-spin (HS) low-spin (LS) transition...

The expected 3D and 2D topologies resulting from combining approximately linear bis- or monopyridyl ligands with [FeIIMII(CN)4] (MII = Pt, Pd, Ni) 4,4-grid sheets are well established. We show here the magnetic structural consequences of incorporating a bent bispyridyl linker ligand in combination [FeIIPtII(CN)4] to form material [Fe(H2O)2Fe(DPSe)2(Pt(CN)4)2]·3EtOH (DPSe 4,4′-dipyridylselenide). Structural investigations reveal an unusual connectivity loosely resembling Hofmann topology...

A family of iron(III) spin crossover complexes with different counteranions, [Fe(qsal-F)2]A (qsal-F = 4-fluoro-2-[(8-quinolylimino)methyl]phenolate; PF6– 1, OTf– 2, NO3– 3, ClO4– 4, BF4– 5, or NCS– 6) have been prepared. All compounds are isostructural and crystallize (triclinic P1̅ space group) two independent centers (Fe1 Fe2) in the asymmetric unit. No solvent molecules found crystal lattice, allowing us to directly probe relative influence anion variation on characteristics. The packing...

We investigate the effects of a broad array external stimuli on structural, spin-crossover (SCO) properties and nature elastic interaction within two-dimensional Hofmann framework material [Fe(cintrz)2Pd(CN)4]·guest (cintrz = N-cinnamalidene 4-amino-1,2,4-triazole; A·guest; guest 3H2O, 2H2O, Ø). This exhibits delicate balance between ferro- antiferro-elastic characters; we show that manipulation pore contents across guests Ø can be exploited to regulate this balance. In A·3H2O, dominant...

Abstract Four isostructural one‐dimensional polymeric iron(II) spin crossover materials containing the ligand 2‐chloro‐4,6‐bis(dipyrid‐2‐ylamino)‐1,3,5‐triazine (cddt) have been synthesised and magnetically structurally characterised. The material Fe(NCS) 2 · n (guest) ( 1 ), self assembles into three crystallographically distinct phases; compounds 1b 1c , [Fe(NCS) (cddt)] 2(CH 3 OH), are polymorphs, however, 1a 1/2(CHCl ) (H O) contains a different solvent system. Each phase shows very...

A family of spin crossover cobalt(II) complexes the type [Co(terpyRX)(2)](Y)(2) x nH(2)O (X = 4, 8, 12 and Y BF(4)(-), ClO(4)(-), PF(6)(-), BPh(4)(-)) has been synthesized, whereby alkyl chain length, RX, counteranion, Y, have systematically varied. The structural (single crystal X-ray diffraction) electronic (magnetic susceptibility, electron paramagnetic resonance (EPR)) properties investigated within this compounds. Single diffraction analysis [Co(terpyR8)(2)](ClO(4))(2),...