Adenosine diphosphate (ADP) plays a crucial role in cell biochemistry, especially in metabolic pathways and energy storage. ADP itself, as well as many of its analogues, such as adenosine hypodiphosphate (AhDP), has been studied extensively, in particular in terms of enzymatic activity. However, structural studies in the solid state, especially for AhDP, are still missing. An analogue of ADP, i.e. adenosine hypodiphosphate ester, has been synthesized and characterized in the crystalline form as two hydrated sodium salts of 2':3'-isopropylideneadenosine 5'-hypodiphosphate (HAhDP, CHNOP for the neutral form), namely pentasodium tetrakis(2':3'-isopropylideneadenosine 5'-hypodiphosphate) tetracosahydrate, 5Na·3CHNOP·CHNOP·24HO or Na(HAhDP)(HAhDP)·24HO, (I), and sodium tetrakis(2':3'-isopropylideneadenosine 5'-hypodiphosphate) pentadecahydrate, Na·CHNOP·2CHNOP·CHNOP·15HO or Na(HAhDP)(HAhDP)(HAhDP)·15HO, (II). Crystal structure analyses of (I) and (II) reveal two nucleoside hypodiphosphate ions in the asymmetric units with different ionization states of the hypodiphosphate unit and adenine base. For all AhDP nucleotides, the same anti conformation about the N-glycosidic bond and similar puckering of the ribose ring have been found. AhDP geometry and interactions have been compared to ADP nucleotides deposited in the Cambridge Structural Database. The adenine-hypodiphosphate interactions, identified as defining nucleotide self-assembly, have been analysed in model systems, i.e. the adenine (Ade) salts of hypodiphosphoric acid, namely bis(adeninium) hypodiphosphate dihydrate, 2CHN·HPO·2HO or (AdeH)(HPO)·2HO, (III), and bis(adeninium) hypodiphosphate, 2CHN·HPO or (AdeH)(HPO), (IV).

A solvothermal reaction between Ln(NO)·6HO (Ln: Gd, Tb and Dy), 2-hydroxy-1-naphthaldehyde, 2-OH-naphth, and ethylenediamine, en, in MeOH in the presence of a base, NEt, led to the formation of the 1D coordination polymers [Ln(L)(MeO)(MeOH)]·MeOH (Ln = Gd (1·MeOH), Tb(2), Dy (3·MeOH); HL = 1,1'-((1E,1'E)-(ethane-1,2-diylbis(azanylylidene))bis(methanylylidene))bis(naphthalen-2-ol), the Schiff-base ligand derived from the condensation of 2-OH-naphth and en), while a similar reaction in an excess of NaN yielded 1D coordination polymers [Ln(L)(N)(MeO)(MeOH)] (Ln = Gd (4), Tb (5), Dy (6)). Finally, upon replacing ethylenediamine with o-phenylenediamine, o-phen, we managed to isolate the discrete dimers [Dy(L')(MeOH)]·2MeOH (7·2MeOH) and [Gd(L')(MeOH)]·2MeOH (8·2MeOH) (HL' = 1,1'-((1E,1'E)-(1,2-phenylenebis(azanylylidene))bis(methanylylidene))bis (naphthalen-2-ol), the Schiff-base ligand from the condensation of 2-OH-naphth and o-phen). Polymers 1-3 describe one-dimensional chains, containing alternating seven- and eight-coordinate Ln metal centers, polymers 4-6 contain eight-coordinate lanthanide ions, while in both 7 and 8 the two Ln centers are eight- and seven-coordinate, adopting square antiprismatic and "piano-stool" geometry, respectively. The magnetocaloric properties of the three Gd analogues were determined from magnetic measurements, yielding the magnetic entropy change -ΔS = 21.8, 23.0 and 16.0 J kg K at T = 3.0 K on demagnetization of 7 T to 0, for 1, 4 and 8, respectively. The study of the magnetic properties also revealed that all three Dy analogues (3, 6 and 7) display out-of-phase signals, therefore suggesting slow magnetic relaxation, while such behaviour was not established in the Tb analogues.

Employment of H3L (= 2-(β-naphthalideneamino)-2-hydroxymethyl-1-propanol) in mixed-metal copper-lanthanide cluster chemistry has led to the isolation of four new enneanuclear heteronuclear isostructural [Cu₇(II)Ln₂(III)] complexes. More specifically, the solvothermal reaction of Cu2(OAc)4·2H2O with H3L and the corresponding lanthanide nitrate salt in MeCN in the presence of a base, NEt3, yielded three complexes with the general formula [Cu₇(II)Ln₂(III)(L)4(HL)2(OAc)4]·2MeCN (Ln: Gd, 1·2MeCN; Tb, 2·2MeCN; Dy, 3·2MeCN), while in addition the Y(III) analogue, [Cu₇(II)Y₂(III)(L)4(HL)2(OAc)4]·2MeCN (4·2MeCN), was also synthesized in the same manner. The structure of the cluster describes two corner-sharing [Cu3Ln] cubane metallic units, each one further connected to one Cu(II) ion. Dc magnetic susceptibility studies in the 5-300 K range for complexes 1-4 reveal the presence of both ferromagnetic and antiferromagnetic exchange interactions within the metallic clusters.

The preparation, structural characterization, EPR spectroscopy and magnetic structural correlation of two Cu(ii) coordination polymers are reported.

The present paper reports the crystal structures of two short phosphonotripeptides (one in two crystal forms) containing one ΔPhe (dehydrophenylalanine) residue, namely dimethyl (3-{[tert-butoxycarbonylglycyl-α,β-(Z)-dehydrophenylalanyl]amino}propyl)phosphonate, Boc(0)-Gly(1)-Δ(Z)Phe(2)-α-Abu(3)PO3Me2, C21H32N3O7P, (I), and diethyl (4-{[tert-butoxycarbonylglycyl-α,β-(Z)-dehydrophenylalanyl]amino}butyl)phosphonate, Boc(0)-Gly(1)-Δ(Z)Phe(2)-α-Nva(3)PO3Et2, as the propan-2-ol monosolvate 0.122-hydrate, C24H38N3O7P·C3H8O·0.122H2O, (II), and the ethanol monosolvate 0.076-hydrate, C24H38N3O7P·C2H6O·0.076H2O, (III). The crystals of (II) and (III) are isomorphous but differ in the type of solvent. The phosphono group is linked directly to the last Cα atom in the main chain for all three peptides. All the amino acids are trans linked in the main chains. The crystal structures exhibit no intramolecular hydrogen bonds and are stabilized by intermolecular hydrogen bonds only.