The supramolecular structure of a cadmium complex with the new functionalized terpyridine ligand 4'-[4-(pyrimidin-5-yl)phenyl]-2,2':6',2''-terpyridine (L1): aqua(L1-κ³N,N',N'')(nitrato-κ²O,O')(nitrato-κO)cadmium(II) dihydrate.

The monomeric title compound, aqua(nitrato-κ²O,O')(nitrato-κO){4'-[4-(pyrimidin-5-yl)phenyl]-2,2':6',2''-terpyridine-κ³N,N',N''}cadmium(II) dihydrate, [Cd(NO3)2(C25H17N5)(H2O)]·2H2O, consists of a seven-coordinated CdII centre bound to the novel 4'-[4-(pyrimidin-5-yl)phenyl]-2,2':6',2''-terpyridine (L1) ligand (behaving as a tridentate chelate), two nitrate anions (as chelating-bidentate and monodentate ligands) and a water O atom. Both chelating groups define the base of a slightly deformed pentagonal bipyramid, while the monocoordinated ligands occupy the apices. The four heterocycles in L1 form a planar skeleton, while the central benzene ring is rotated from this planar geometry by more than 30°, probably because of packing effects. Noncovalent interactions lead to the formation of columnar arrays parallel to [100].

Synthesis of azanucleosides through regioselective ring-opening of epoxides catalyzed by sulphated zirconia under microwave and solvent-free conditions.

New azanucleosides were obtained using sulphated zirconia (ZS) as catalyst in the nucleophilic oxirane ring opening reaction of 1-allyl-3-(oxiran-2-ylmethyl) pyrimidine-2,4(1H,3H)-dione and 1-allyl-5-methyl-3-(oxiran-2-ylmethyl)-pyrimidine-2,4(1H,3H)-dione, with (S)-prolinol. The new templates were obtained with good yields following a route which exploits the reactivity of epoxides in the presence of sulphated zirconia as catalyst. The key step was carried out using microwave and solvent-free conditions and proceeds with high selectivity.

Monodentate and bridging behaviour of the sulfur-containing ligand 4'-[4-(methylsulfanyl)phenyl]-4,2':6',4''-terpyridine in two discrete zinc(II) complexes with acetylacetonate.

The Zn complexes bis(acetylacetonato-κ(2)O,O')bis{4'-[4-(methylsulfanyl)phenyl]-4,2':6',4''-terpyridine-κN(1)}zinc(II), [Zn(C(5)H(7)O(2))(2)(C(22)H(17)N(3)S)(2)], (I), and {µ-4'-[4-(methylsulfanyl)phenyl]-4,2':6',4''-terpyridine-κ(2)N(1):N(1'')}bis[bis(acetylacetonato-κ(2)O,O')zinc(II)], [Zn(2)(C(5)H(7)O(2))(4)(C(22)H(17)N(3)S)], (II), are discrete entities with different nuclearities. Compound (I) consists of two centrosymmetrically related monodentate 4'-[4-(methylsulfanyl)phenyl]-4,2':6',4''-terpyridine (L1) ligands binding to one Zn(II) atom sitting on an inversion centre and two centrosymmetrically related chelating acetylacetonate (acac) groups which bind via carbonyl O-atom donors, giving an N(2)O(4) octahedral environment for Zn(II). Compound (II), however, consists of a bis-monodentate L1 ligand bridging two Zn(II) atoms from two different Zn(acac)(2) fragments. Intra- and intermolecular interactions are weak, mainly of the C-H···π and π-π types, mediating similar layered structures. In contrast to related structures in the literature, sulfur-mediated nonbonding interactions in (II) do not seem to have any significant influence on the supramolecular structure.

The Heck reaction of allylic alcohols catalysed by an N-heterocyclic carbene-Pd(ii) complex and toxicity of the ligand precursor for the marine benthic copepod Amphiascoides atopus.

The palladium-catalysed reaction of aryl halides and allylic alcohols is an attractive method for obtaining α,ß-unsaturated aldehydes and ketones, which represent key intermediates in organic synthesis. In this context, a 1,2,3-triazol-5-ylidene (aNHC)-based palladium(ii) complex formed in situ has been found to be a selective catalyst for the syntheses of building blocks from the corresponding aryl halides and allylic alcohols, with yields ranging from 50% to 90%. The lack of toxic effects of the ligand precursor (1,2,3-triazolium salt) of the palladium(ii) complex for the harpacticoid copepod Amphiascoides atopus allowed us to contrast the efficiency of the catalytic system with the potential impact of the principal waste chemical in global aquatic ecosystems, which has not been previously addressed.

Highly efficient macrolactonization of ω-hydroxy acids using benzotriazole esters: synthesis of Sansalvamide A.

A facile and mild macrolactonization reaction of ω-hydroxy acids was developed based on the transesterification of benzotriazole esters. Treatment of ω-hydroxy acids with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) and 1-hydroxy benzotriazole (HOBT) in chloroform provided macrolactones in excellent yields. The reactions were performed under basic, neutral and acidic conditions using N,N-dimethylaminopyridine (DMAP), tetrabutylammonium tetrafluoroborate (TBABF(4)) and BF(3)·Et(2)O, respectively. A calcined hydrotalcite was also used instead of DMAP. Finally, to test the scope of the protocol in the synthesis of biologically relevant macrolactones, the total synthesis of Sansalvamide A was carried out.

Structural characterization of a hybrid terpyridine-pyrazine ligand and its one-dimensional ZnII coordination polymer: a computational approach to conventional and nonconventional intermolecular interactions.

The structures of a new hybrid terpyridine-pyrazine ligand, namely 4'-[4-(pyrazin-2-yl)phenyl]-4,2':6',4''-terpyridine (L2), C25H17N5, and its one-dimensional coordination polymer catena-poly[[bis(acetylacetonato-κ2O,O')zinc]-µ-4'-[4-(pyrazin-2-yl-κN4)phenyl]-4,2':6',4''-terpyridine-κN1], [Zn(C5H7O2)2(C25H17N5)]n or [Zn(acac)2(L2)]n (Hacac is acetylacetone), are reported. Packing interactions in both crystal structures are analyzed using Hirshfeld surface and enrichment ratio techniques. For the simpler structure of the monomeric ligand, further studies on the interaction hierarchy using the energy framework approach were made. The result was a complete picture of the intermolecular interaction landscape, which revealed some subtle details, for example, that some weak (at first sight negligible) C-H...N interactions in the structure of free L2 play a relevant role in the crystal stabilization.

Structural and theoretical characterization of a new twisted 4'-substituted terpyridine compound: 4'-(isoquinolin-4-yl)-2,2':6',2''-terpyridine.

4'-Substituted derivatives of 2,2':6',2''-terpyridine with N-containing heteroaromatic substituents, such as pyridyl groups, might be able to coordinate metal centres through the extra N-donor atom, in addition to the chelating terpyridine N atoms. The incorporation of these peripheral N-donor sites would also allow for the diversification of the types of noncovalent interactions present, such as hydrogen bonding and π-π stacking. The title compound, C24H16N4, consists of a 2,2':6',2''-terpyridine nucleus (tpy), with a pendant isoquinoline group (isq) bound at the central pyridine (py) ring. The tpy nucleus deviates slightly from planarity, with interplanar angles between the lateral and central py rings in the range 2.24 (7)-7.90 (7)°, while the isq group is rotated significantly [by 46.57 (6)°] out of this planar scheme, associated with a short Htpy...Hisq contact of 2.32 Å. There are no strong noncovalent interactions in the structure, the main ones being of the π-π and C-H...π types, giving rise to columnar arrays along [001], further linked by C-H...N hydrogen bonds into a three-dimensional supramolecular structure. An Atoms In Molecules (AIM) analysis of the noncovalent interactions provided illuminating results, and while confirming the bonding character for all those interactions unquestionable from a geometrical point of view, it also provided answers for some cases where geometric parameters are not informative, in particular, the short Htpy...Hisq contact of 2.32 Što which AIM ascribed an attractive character.

A temperature-induced order-disorder phase transition in a 4-substituted 4,2':6',4''-terpyridine.

Crystals of 4'-(isoquinolin-4-yl)-4,2':6',4''-terpyridine (iqtp), C24H16N4, grown from an ethanol solution, undergo a reversible first-order single-crystal to single-crystal phase transition at Tc in the range 273-275 K, from a disordered higher-temperature phase [form (I)] in the space group P21/c, with one single molecule in the asymmetric unit, to an ordered lower-temperature one [form (II)] in the space group P21/n, with two independent molecules in the asymmetric unit. There is a group-subgroup relationship linking (I)-(II), due to cell doubling and the disappearance of a number of symmetry operations. In addition to X-ray diffraction, the transition has been monitored by Raman spectroscopy and differential scanning calorimetry, the latter disclosing an enthalpy change of 0.72 (6) kJ mol(-1). Variations of the unit-cell parameters with temperature between 170 and 293 K are presented. The evolution of diffraction spots in the vicinity of the transition temperature shows the coexistence of both phases, confirming the first-order character of the transition. Structural details of both phases are analyzed and intermolecular interactions compared in order to investigate the mechanism of the phase transition. A three-dimensional Hirshfeld surface analysis was performed to corroborate the significant changes in the intermolecular features.

Three new diarylbutane lignans from the resin of Bursera fagaroides.

Three new diarylbutane lignans, named 9-acetyl-9'-pentadecanoil-dihydroclusin (1), 2,3-demethoxy-secoisolintetralin monoacetate (4) and dihydroclusin monoacetate (5), have been isolated from the resin of Bursera fagaroides, together with two known ones, 2,3-demethoxy-secoisolintetralin diacetate (2) and dihydroclusin diacetate (3). The complete structure assignments were obtained by means of (1)H and (13)C NMR spectra.