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By modulating the secondary building units derived from the primary building units, N-acylsalicylhydrazides (H3xshz), we have been able to construct isostructural but tunable host networks, [Mn6(xshz)6(dmf)2(bpea)2], with different cavity sizes and shapes where the secondary building units, [Mn6(xshz)6], were linked through exo-bidentate bridging ligand, 1,2-bis(pyridyl)ethane (bpea) to form 3-D networks. With a short length linear N-acyl side chain at the primary building unit, the host networks have a 3-D network with three-dimensional cavities. With an appropriate length linear N-acyl side chain at the primary building unit, the host network keeps the isostructural 3-D network but with two types of one-dimensional channels of reduced cavity volume. The tuned host networks showed not only size selectivity for the guest molecules but also shape selectivity. While the three-dimensional channeled host showed selectivity depending on the length of the podal guests, the one-dimensional channeled host showed selectivity depending on both the length and/or the podality of the guest molecules. [ABSTRACT FROM AUTHOR]

By using the tripodal tetradentate ligand tris(2-benzimidazolylmethyl)amine (H[sub 3]ntb), which can have several charge states depending on the number of secondary amine protons, mononuclear octahedral and dinuclear trigonal bipyramidal Fe(lll) complexes were prepared. The reaction of mononuclear octahedral [Fe[sup III](H[sub 3]ntb)Cl[sub 2]]ClO[sub 4], 1, with 3 equiv of sec-butylamine in methanol led to the formation of mononuclear cis-dimethoxo octahedral Fe[sup III](H[sub 2]ntb)(OMe)[sub 2], 2. One equivalent of the sec-butylamine was used to generate the monoanionic H[sub 2]ntb[sup -] ligand where one of the three amines in the benzimidazolyl groups was deprotonated. The remaining 2 equiv were used to generate two methoxides that were coordinated to the octahedral Fe(lll) ion in a cis fashion as demonstrated by the chlorides in 1. Reaction of 1 with excess (7 equiv) sec-butylamine generated the doubly deprotonated dianionic Hntb[sup 2-] that stabilized the dinudear μ-oxo Fe[sup III][sub 2]O(Hntb)[sub 2], 3, adopting a five-coordinate trigonal bipyramidal geometry. The magnetic data for 3 are consistent with the antiferromagnetically coupled Fe[sup III] (S = 5/2) sites with the coupling constant J = -127 cm[sup -1]. [ABSTRACT FROM AUTHOR]

A novel S4-symmetric icosanuclear manganese metalladiazamacrocycle was synthesized using a pentadentate ligand, N-3-phenyl- trans-2-propenoylsalicylhydrazide (H3L), that has a rigid and bulky terminal N-acyl group. A 20 cyclic repeat of an -(Mn-N-N)- linkage resulted in a highly puckered diaza-bridged 60-membered icosanuclear metallamacrocycle. The steric interaction between the ligands in the cyclic system leads to five consecutive MnIII centers in a chemically different -(MnAMnBMnCMnDMnE)- environment, with the chiralities of the metal centers being in a rather complicated -(ΛΛΔΛΛ)(ΔΔΛΔΔ)- sequence. [ABSTRACT FROM AUTHOR]

We report on helical coordination networks that were prepared using a hexanuclear manganese metallamacrocycle as a helical tecton. We were able to prepare the three-dimensional helical coordination networks using a hexanuclear manganese metallamacrocycle, [Mn6(Ishz)6], as a helical tecton, where N-lauroyl salicylhydrazide (H3lshz) was used as the primary building unit to generate the helical tecton as a secondary building unit. While the 41/43 screw symmetry-linked helical coordination network was obtained when the primary building units had an N-acetyl group, both the 31/32 screw symmetry-linked and the 41/43 screw symmetry-linked helical coordination networks were obtained simultaneously in the same batch when the primary building unit had a long alkyl N-lauroyl group at the N-acetyl site. [ABSTRACT FROM AUTHOR]

Discrete metal-organic polyhedra (MOP) with nanosized cavities and/or clusters of MOP could be prepared when C3-symmetric facial ligands and a potential hexatopic Cu(II) ion are combined in the presence of perchlorate as a weak linker, while similar reaction conditions in the presence of a nitrate linker led to extended metal-organic frameworks made of MOP as supramolecular building blocks. [ABSTRACT FROM AUTHOR]

Flexible metal-organic frameworks (MOFs) show the structural transition phenomena, gate opening and breathing, upon the input of external stimuli. These phenomena have significant implications in their adsorptive applications. In this work, we demonstrate the direct capture of these gate-opening and breathing phenomena, triggered by CO2 molecules, in a well-designed flexible MOF composed of rotational sites and molecular gates. Combining X-ray single crystallographic data of a flexible MOF during gate opening/closing and breathing with in situ X-ray powder diffraction results uncovered the origin of this flexibility. Furthermore, computational studies revealed the specific sites required to open these gates by interaction with CO2 molecules. [ABSTRACT FROM AUTHOR]

Either an S8 symmetrical 48-membered hexadecanuclear or an S10 symmetrical 60-membered icosanuclear manganese metallamacrocycle was self-assembled using a manganese ion and a ditopic pentadentate ligand. This was either N-4-phenylbenzoylsalicylhydrazide (H3pbshz) containing a rigid rod-shaped, bulky biphenyl residue as a terminal N-acyl group or N-3,3-diphenylpropionylsalicylhydrazide (H3dppshz) containing a flexible β-branched N-acyl group, but with two sterically bulky phenyl residues at the Cβ position. The backbone of these metal-organic assemblies is a repeating unit consisting of a -[Mn-N-N-] link that extends to complete either the 48-membered cyclic structure involving 16 manganese(lll)centers and 16 ditopic linker ligands or the 60-membered cyclic structure involving 20 manganese(lll) centers and 20 ditopic linker ligands (depending on the ligand used). Even though the nuclearity of the metallamacrocycles was different, the successive manganese centers were in the same chiral sequence, ··· (ΛΛΛΛ)(ΛΛΛΛ)···. [ABSTRACT FROM AUTHOR]