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Assemblies between pseudo-enantiomers with different d8metal centers, Δ-[M(bpy){Co(aet)2(R-pn)}]3+(M = Pd or Pt, bpy = 2,2′-bipyridine, aet = 2-aminoethanethiolate, pn = 1,2-propanediamine), and Λ-[M′(bpy){Co(aet)2(S-pn)}]3+(M′ ≠ M, M′ = Pd or Pt), have been examined from stereo- and spectrochemical aspects. A mixture of equimolar amounts of the optically active sulfur-bridged dinuclear complex, Δ-[M(bpy){Co(aet)2(R-pn)}](NO3)3·7H2O, and its pseudo-enantiomer, Λ-[M′(bpy){Co(aet)2(S-pn)}](NO3)3·7H2O, in H2O crystallizes as [M(bpy){Co(aet)2(R-pn)}][M′(bpy){Co(aet)2(S-pn)}](NO3)6·4H2O, in which two complex cations with imperfect enantiomorphisms form a 1 : 1π–πstacked unit. [ABSTRACT FROM AUTHOR]

Reaction of trans(N)-[Co(D-pen)2]- (pen = penicillaminate) or trans(N)-[Co(L-pen)2]- with [MCl2(L)] {M = Pd or Pt, L = 2,2'-bipyridine (bpy) or 1,10-phenanthroline (phen)} in the presence of tetrafluoroborate stereoselectively gave an optically active S-bridged dinuclear complex, [M(L){Co(D-pen)2}]BF4 · 2H2O or [M(L){Co(L-pen)2}]BF4 · 2H2O. The mixture of equimolar amounts of these enantiomers in H2O crystallizes as [M(L){Co(D-pen)2}]0.5[M(L){Co(L-pen)2}]0.5BF4 · 4H2O (DLbpyM · 4H2O, DLphenM-A · 4H2O), in which the enantiomeric complex cations are included by the ratio of 1 : 1. In crystals of DLbpyM · 4H2O and DLphenM-A · 4H2O, [M(L){Co(D-pen)2}]+ and [M(L){Co(L-pen)2}]+ interact stereospecifically with each other through π-conjugated systems to form dimeric structures. Other racemic crystals with the same chemical compositions as DLphenM-A · 4H2O, DLphenM-B · 4H2O, were obtained from equimolar amounts of [M(phen){Co(D-pen)2}]+ and [M(phen){Co(L-pen)2}]+ in aqueous acetonitrile solution. In the crystals of DLphenM-B · 4H2O, [M(phen){Co(D-pen)2}]+ and [M(phen){Co(L-pen)2}]+ are arranged alternately while overlapping phen planes, and the π electronic systems of phen interact with each other. Although stereospecific hydrogen bonds between the coordinated -NH2 and -COO- groups are formed in both DLphenM-A · 4H2O and DLphenM-B · 4H2O, their bonding modes differ noticeably from each other. As a result, DLphenM-A · 4H2O builds up 1-D ladder-like networks due to the stereospecific π-π stackings and hydrogen bondings between enantiomers, while 2-D sheet-like networks are established for DLphenM-B · 4H2O. [ABSTRACT FROM AUTHOR]

The one-pot reaction of N,N′ -bis(3-methoxysalicylidene)-1,4-diaminobutane (MeOsalbnH 2), zinc(II) perchlorate, and lanthanide(III) acetate by a molar ratio of 2:2:1 affords a novel heterotrinuclear Zn 2 Ln (Ln: La, Sm, Eu, Tb) complex formulated as [Ln(CH 3 COO) 2 {Zn(MeOsalbn)} 2 ]ClO 4. The La(III) complex exhibits a bright blue fluorescence, while the Sm(III) complex shows a reddish-orange coloured f–f photoluminescence. The one-pot reaction of N,N′ -bis(3-methoxysalicylidene)-1,4-diaminobutane (MeOsalbnH 2), zinc(II) perchlorate, and lanthanide(III) acetate by a molar ratio of 2:2:1 affords a heterotrinuclear Zn 2 Ln (Ln: La, Sm, Eu, Tb) complex formulated as [Ln(CH 3 COO) 2 {Zn(MeOsalbn)} 2 ]ClO 4. In this complex, the central Ln(III) atom is bridged by two {Zn(MeOsalbn)} units and two acetate ligands to form ten-coordination environment. Each Zn(II) atom is coordinated by MeOsalbn2− through the N 2 O 2 site and one oxygen atom from the bridging acetate to afford a five-coordination geometry. In the crystalline state at room temperature, the La(III) complex exhibits a bright blue fluorescence, while the Sm(III) complex shows a reddish-orange colored f–f photoluminescence via an energy transfer from the T 1 state localized on the {Zn(MeOsalbn)} units to the acceptor level of the central Sm(III) ion. The results of TD-DFT calculations show that the lowest excited singlet state or triplet state involved in photoluminescence of the La(III) or Sm(III) complex has some intramolecular charge-transfer (CT) character from the phenoxo or methoxy groups to the imino groups in the coordinated MeOsalbn2− moieties. [ABSTRACT FROM AUTHOR]

• Four novel helical and non-helical dinuclear zinc(II) complexes have been prepared. • Structures of the complexes were determined by single crystal X-ray analyses. • The complexes were characterized by spectroscopic methods and DFT calculations. • The structural characteristics reflect the solid-state spectral behaviours. The reaction of bis(N -salicylidene)-4,4′-diaminodiphenyl)ether (4OsalH 2) with zinc(II) ion affords a 2:2 dinuclear zinc(II) complex formulated as [Zn 2 (4Osal) 2 ]. A similar 2:2 dinuclear zinc(II) complex, [Zn 2 (4Ssal) 2 ], can be obtained by the reaction of bis(N -salicylidene)-4,4′-diaminodiphenyl)thioether (4SsalH 2) with zinc(II) ion. These two complexes, [Zn 2 (4Osal) 2 ] and [Zn 2 (4Ssal) 2 ], take similar helical structures. Although bis(N -salicylidene)-3,3′-diaminodiphenyl)methane (3MsalH 2) and bis(N -salicylidene)-2,2′-diaminodiphenyl)thioether (2SsalH 2) give dinuclear complexes with similar compositions, [Zn 2 (3Msal) 2 ] and [Zn 2 (2Ssal) 2 ], respectively, their structures are quite different from those of [Zn 2 (4Osal) 2 ] and [Zn 2 (4Ssal) 2 ]. Namely, [Zn 2 (3CH 2 sal) 2 ] and [Zn 2 (2Ssal) 2 ] take the mosocate and the phenoxo-bridged dinuclear structures, respectively. Such structural differences between the formed complexes occur depending on the relative positions of the two amino groups of the precursor dianiline, and reflect their diffuse reflectance and photoluminescence spectral behaviours. It has become clear that the electronic transitions of such a complex strongly depend on the relative arrangement of the two amino groups in the precursor dianiline compound as well as the kind of the central atom linking two aniline frameworks. [ABSTRACT FROM AUTHOR]

Assemblies between the pseudo-enantiomers with different π electronic systems, [Pt(bpy){Co( d -pen) 2 }] + (bpy = 2,2′-bipyridine, pen = penicillaminate) and [M(phen){Co( l -pen) 2 }] + (M = Pt or Pd, phen = 1,10-phenanthroline), or [Pt(bpy){Co( l -pen) 2 }] + and [M(phen){Co( d -pen) 2 }] + , have been examined from stereo- and spectrochemical aspects. As a result, a mixture of equimolar amounts of optically active sulfur-bridged dinuclear complex, [Pt(bpy){Co( d -pen) 2 }]Cl, and its pseudo-enantiomer, [M(phen){Co( l -pen) 2 }]Cl, in H 2 O crystallizes as [Pt(bpy){Co( d -pen) 2 }][M(phen){Co( l -pen) 2 }]Cl 2 ·14H 2 O, in which two complex cations with imperfect enantiomorphisms form a 1:1 π–π stacked unit. In the crystal, such a 1:1 π–π stacked unit develops into a linear-chain through further π–π stacking contacts with adjacent 1:1 π–π stacked units. [ABSTRACT FROM AUTHOR]

Abstract: The optically active S-bridged dinuclear complex, [Pt(bpy){Co(d-pen)2}]X (1X: bpy=2,2′-bipyridine; pen=penicillaminate; , , Br−, or I−), and its enantiomer, [Pt(bpy){Co(l-pen)2}]X (2X), were prepared by the reactions of [PtCl2(bpy)] with K[Co(d-pen)2] and K[Co(l-pen)2], respectively. The racemates, [Pt(bpy){Co(d-pen)2}]0.5[Pt(bpy){Co(l-pen)2}]0.5X (3X), were also obtained by the slow evaporation of aqueous solutions containing equimolar amounts of 1X and 2X. The crystal structures of 3NO3 ·3H2O, 3ClO4 ·2H2O, 3Br·2H2O and 3I·5.5H2O were determined by X-ray crystallography, and compared with those of 1ClO4 ·H2O, 1Br·2H2O, 1I·2H2O, 2ClO4 ·H2O, 2Br·2H2O and 2I·2H2O. The optically active complexes 1X and 2X exist as monomers, accompanied by no intermolecular interactions in the π-electronic systems of the bpy moieties. In the crystals of 3Br·2H2O, on the other hand, the enantiomeric complex cations, [Pt(bpy){Co(d-pen)2}]+ ( D ) and [Pt(bpy){Co(l-pen)2}]+ ( L ), are arranged alternately with overlapping bpy planes along the c axis, and the π electronic system of the bpy framework in D interacts with those in L . The remaining three racemates, 3NO3 ·3H2O, 3ClO4 ·2H2O and 3I·5.5H2O, afford dimeric structures with π–π stacking contacts between the enantiomeric D and L complex cations. Differences in the crystal structures between the optically active complexes and the racemates significantly mirror the diffuse reflectance spectral behaviors. [Copyright &y& Elsevier]