We have been interested in in layered structures of dipicolinate complexes constructed by π-π interactions and also to generalize the interlayer separation while encapsulating organo-cations. A series of study carried out whose slides are listed below:

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stacking interactions

π-π stacking generally observed in bis-dipicolinates

Cation intercalation in layered anionic frameworks, Cationic ligands and assembling of complex ions

Background: We have carried out extensive work on layered structures from anion assemblies of metal dipicolinates to encapsulate organocations

Packing diagram of the complexes showing the [ML2]2- (ball and stick mode) as inorganic layer and amines (space filled mode) as organic layer. En = ethylenediamine, pen =1,5-pentanediamime , bam = 4-aminobenzylamine, doc = 1,8-diaminodecane

Inorg. Chim. Acta 363 (2010) 1479; Inorg. Chem. Commun. 13 (2010) 350

[enH2][NiL2].3H2O

[penH2][CuL2].5H2O [bamH]2[NiL2].5H2O

[enH2][M(en)2(H2O)2].[CuL2]2.H2O [docH2][CuL2].2H2O

{[Na(H2O)2]2[CuL2].2H2O}n {[K2(H2O)7][CuL2]}n

Packing diagram of dipicolnate complexes with alkali metal ions:

{Ca(H2O)4][CuL2].2H2O}n [Mg(H2O)5][CuL2].2H2O

Inorg. Chim. Acta 363 (2010) 1479

Packing diagram showing intercalation of histidinium and ornithinium cations: (A-B-A manner)

[L-orniH2][CoL2].9H2O [L-hisH2][CuL2].5H2O

Polyhedron 30 (2011) 22

Complex Cation of Inter-layer separation (Å)

[enH2][NiL2].3H2O ethylenediamine 8.2

[pnH2][CuL2].xH2O* 1,3-propanediamine 10.4

[penH2][CuL2]. 5H2O 1,5-diaminopentane 11.2

[L-orniH2][CoL2].9H2O L-ornithine 11.5

[L-hisH2][CuL2].5H2O L-histidine 11.8

[bamH]2[CuL2].5H2O 4-amino benzyl amine 14.3

Inter-layer separation generated by amines and amino acid dications :

Mn(II) / Cu(II) dipicolinate with adeninium cations and their supramolecular architectures:

Cryst. Growth Des. 10 (2010) 3242

ORTEP diagram of [1H, 9H-ade][3H,7H-ade][CuL2].3H2O

Adeninium ribbon in layers of complex anion

Close view of 1D zigzag adeninium ribbon with H-bond distances

Mn(II)-dipicolinate with cytosinium cations and its supramolecular architectures:

Packing diagram of [1H, 3H-cyt]2 [MnL2(H2O)].2cyt.6H2O viewed along a axis

ORTEP diagram of [1H, 3H-cyt]2

[MnL2(H2O)].2cyt.6H2O

Cryst. Growth Des. 10 (2010) 3242

Close view of tetrameric hydrogen bonded assembly of cytosine

Stabilization of protonated adenine and cytosine cations in polymeric Mn(II) / Cu(II)-quinolinate complex and in flexible polycarboxylic systems:

Cytosinium cations in layers of {[1H,3H-cyt]2[CuL2] 6H∙ 2O}n

Adeninium cations in layers of {[1H, 9H-ade]2[MnL2].4H2O}n

Discrete cytosine-cytosinium assembly in layers of adipic acid

Trimeric cytosine-cytosinium assembly in layers of citric acid

Inorg. Chem. Commun. 13 (2010) 1244;J. Mol. Struct. 1001 (2011) 134

(a) (b) (c)

(d)

In the present study we have determined structures of few nickel complexes and demonstrate the stacking of (a) (HQ)2[NiL2].5H2O, (b) (H5AQ)2[NiL2].4H2O, (c) (H8HQ)2[NiL2].6H2O, (d) H2[NiL2].4H2O. ([NiL2]2- in ball and stick mode, in a-c cations are in space filled mode). Where Q = quinoline, 8HQ = 8-hydroxyquinoline, 5AQ = 5-aminoquinoline. This happens as the quinolines have greater tendency for π-stacking interactions.

H2[NiL2].3H2OQuinoline

Solid State(HQ)2[NiL2].5H2O

(H5AQ)2[NiL2].4H2O

5-aminoquinoline

(Washed with MeOH)

Solid State

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We also establish the solid state cation exchange reactions shown below:

M(OAc)2 + LH2 + Cat [(CatH)(ML2)]n (nH2O)m + AcOH

When M = Mn(II) Cat = adenine m = 4 1 M = Cu(II) Cat = cytosine m = 6 2

MeOH

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Cationic sodium cluster [Na4(μ-H2O)6(H2O)10]4+

Coordination of cationic sodium cluster [Na4(μ-H2O)6(H2O)10]4+

[Mg(H2O)5] units are coordinated to dipicolnate complex

[CuL2] dianions are held I by polymeric aqua-bridged sodium cations

[Ca(H2O)4] 2+ units are bridged by the dipicolinate complex anions[CuL2] dianions are hel by polymeric

aqua-bridged potassium cations

Coordination by cationic ligands

Assembling as well as Scrambling:

Combination of copper and cobalt complex ions

Multiple cobalt containing cations and anions