From the reaction between a dinuclear paddle-wheel carboxylate, namely [Cu2mu-(O2CCH2C4H3S)4] (1), and the flexible ligand 1,3-bis(4-pyridyl)propane (BPP) a neutral 2-D coordination polymer [[Cu2(O2CCH2C4H3S)4mu-(BPP)2]]n (2) was obtained. Compounds 1 and 2 were characterized by means of elemental analysis, thermal analysis (TG/DSC), vibrational spectroscopy, and electron paramagnetic resonance (EPR). The crystal structure of 2 reveals that each Cu(II) is coordinated by two nitrogen atoms from different BPP ligands and two 3-thiopheneacetate groups within a distorted square planar geometry in a trans-[N, N, O, O] arrangement. The BPP ligand adopts a TG conformation bridging two copper centers giving rise to a 1-D sinusoidal polymeric chain along the crystallographic c axis. Adjacent 1-D chains are extended into a 2-D coordination network through pairs of monatomic carboxylate bridges in direction of the b axis. This bridging mode affords centrosymmetric dimeric units Cu2O2, and therefore, the copper ions are involved in a CuN2O2O' chromophore displaying a (4 + 1) square pyramidal coordination in the resultant 2-D polymeric network. The polycrystalline X-band EPR spectrum of 2 at room temperature is characteristic of a triplet state with nonnegligible zero-field splitting in agreement with the crystal structure. Crystal data for 2: monoclinic, space group P2(1)/c, a = 9.4253(10) A, b = 10.9373(10) A, c = 23.6378(10) A, beta = 98.733(4) degrees, Z = 2.

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PACS 76.30.Fc, 76.70.Hb, 78.20.Ls, 78.40.Ha Different natural blue and green fluorapatite samples from Brazil were investigated by electron paramagnetic resonance (EPR), optical absorption, photoluminescence and the magnetic circular dichroism of absorption (MCDA). The main objective of our work is to confirm the unusual valence state of Mn (V), with high spin configuration S = 1, in tetrahedral coordination. The EPR spectra measured at low temperatures (10 K -30 K) in X-band (10 GHz) show a complicated structure that can be explained through static Jahn-Teller effect acting on the excited states of Mn (V). Photoluminescence measurements showing a multi line spectrum in the near infrared region caused by transitions between the 1 E -3 A 2 with phonon replica confirm the presence of Mn (V). However, strong evidence for high spin configuration of Mn (V) with S = 1 was found from measurements of the MCDA as a function of temperature and magnetic fields. Using the Brillouin function for the magnetization, a spin S = 1 for the ground state for all optical absorption bands in the visible spectral range was determined, confirming that Mn (V) is responsible for the blue colour in natural fluorapatite.