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Here we report novel bispidine-based coordination polymers (CPs) 2·TCM, 3·TCM, 3·NB, 5·TCM and 5·TCM·NB, of compostition [Mn(Cl)2(L2)2·(TCM)2], [Mn(Cl)2(L3)2·(TCM)5], [Mn(Cl)2(L3)2·(NB)8], [Mn(Cl)2(L5)2·(TCM)4], [Mn(Cl)2(L5)2·(TCM)2·(NB)2], respectively (NB = nitrobenzene; TCM = chloroform). They were obtained starting from novel bispidine ligands L2 (dimethyl 7-isopropyl-3-methyl-9-oxo-2,4-di(pyridin-4-yl)-3,7-diazabicyclo[3.3.1]nonane-1,5-dicarboxylate), L3 (dimethyl 7-(cyclohexylmethyl)-3-methyl-9-oxo-2,4-di(pyridin-4-yl)-3,7-diazabicyclo[3.3.1]nonane-1,5-dicarboxylate) and L5 (dimethyl 7-(4-(dimethylamino)benzyl)-3-methyl-9-oxo-2,4-di(pyridin-4-yl)-3,7-diazabicyclo[3.3.1]nonane-1,5-dicarboxylate), The novel CPs were characterized by single crystal X-ray diffraction (SC-XRD), powder X-ray diffraction (PXRD) and thermal analyses (TGA). We describe their structural and dynamic properties in terms of solvent exchange and adsorption processes, and we outline the general trends observed on the basis of a total of 16 X-ray structures (4 new) and 21 microcrystalline powder phases (10 new), which have been obtained so far for CPs by coordination of ligands L1-L5, having different substitution at the N7 position. This large set of CPs comprises monosolvated, bisolvated and desolvated species, and it shows a good demonstration of how small differences in the functionalization of the organic ligand can have a strong impact on the resulting structural and dynamic properties of this class of 1D CPs.

Pyridine-based bispidine ligands L1-L7, which differ in the substituent at the N7 position of the bispidine scaffold, have been studied by single crystal X-ray diffraction and density functional theory (DFT) calculations, also including solid-state algorithms. Qualitative description of the packing interactions and quantitative data on the stability of each ligand in the solid-state have been employed to draw reasonable predictions on the ligand potential for the formation of linear 1D coordination polymers (CPs) with Mn(ii)Cl 2 and on their resulting dynamic properties, in terms of adsorption and solvent exchange capabilities. The basic assumption lies in the fact that volume and polarizability of the ligands would similarly affect packing energies in both molecular solids and CP materials. The results here obtained confirm the data previously reported on CPs (those made from L4 are less dynamic than the ones with L1), but they also allow the prediction that CPs made with L2 and L5 should be more dynamic than expected, while CPs with L6 and L7 should not form altogether. This latter prediction was derived from the analysis of the steric and electronic factors of the ligand substituents on the N7 position and it is further substantiated by the obtainment of a 2 : 1 molecular complex, and not a CP, by crystallization of L6 with MnCl 2 .

A small family of structural analogues of the antimitotic tripeptides, hemiasterlins, have been designed and synthesized as potential inhibitors of tubulin polymerization. The effectiveness of a multicomponent approach was fully demonstrated by applying complementary versions of the isocyanide-based Ugi reaction. Compounds strictly related to the lead natural products, as well as more extensively modified analogues, have been synthesized in a concise and convergent manner. In some cases, biological evaluation provided evidence for strong cytotoxic activity (six human tumor cell lines) and for potent inhibition of tubulin polymerization.

We report here a two step efficient route for the synthesis of 1,2,3,4-tetrahydro-β-carboline (THBC)-based tetracyclic peptidomimetics from a Ugi 4-CR/Pictet-Spengler reaction sequence. Suitably N-protected 2-aminoacetaldehyde was for the first time applied as the carbonyl component in a Ugi four-component reaction, opening the way to the employment of N-protected α-amino acid-derived aldehydes in the same role. The potential of the obtained scaffolds is related to the possibility of further derivatization with the desired pharmacophoric groups, on both the terminal acid and amine functional groups, for the development of conformationally constrained tryptophan-containing peptide ligands. Extensive molecular modeling and (1)H NMR studies highlighted a robust, folded, β-turn-like conformation for one of these peptidomimetic compounds.