1. Emanuele Priola 1, Elisabetta Bonometti 1, Eliano Diana 1 1 University of Turin, Via Pietro Giuria 7, 10125, Italy, e-mail: emanuele.priola@unito.it Computational model of the fragment Cd(tu) 2 (SCN) 2 (NCS) 2 and simulated spectrum. We used a TD-B3LYP functional on optimized structure, with 631gd set base for light atoms and ecp lan el for Cadmium. The model predicts very accurately the high energy adsorption electronic transitions common for all the family. It is quite interesting that in this case the Cadmium orbitals seem to have a great importance in electronic structure of the solid, different from what is usually said for Cadmium coordination polymers. F REQUENCY ( NM ) O RBITALS INVOLVED AND SYMMETRY OF TRANSITION A SSIGNMENT 280 HOMO-3 -> LUMO+1 1 A u Ligand (SCN - ) to Ligand (tu) (LL) 302 HOMO-3 -> LUMO / HOMO-1 - >LUMO 1 A u Ligand (SCN - and tu) to a mixed state with the participation of s orbitals of Cadmium atom (LMCT) 313 HOMO-1 -> LUMO 1 A u Ligand (SCN - ) to mixed state with the participation of s orbitals of Cadmium atom (LMCT) The research in new materials through the rational design of weak interaction in the solid state is one of the main challenge in modern solid state chemistry and material science. We decided to develop the knowledge of the effects of weak interactions on coordination polymers of cadmium thiocyanate. This salt proved to be a good inorganic framework for coordination polymers [1], and with the choise of appropriate ancillary ligands it is possible to obtain different rational topologies and new materials with luminescence and NLO properties [2]. We decide to analize the effects of steric hindrance (more or less isotropic), hydrogen bond, pi-pi stacking and presence of halogens with the use of a very versatile family of organic ligands : N-substituted tioureas. We obtained five new compounds and we rationalize in this framework also three compounds yet reported in litterature: [Cd(SCN) 2 (tu) 2 ] n (1)[3], [Cd(SCN) 2 (tu)] n (2), [Cd(SCN) 2 (tu) 2 (H 2 O)] n (3)[4], [Cd(SCN) 2 (N-metiltu) 2 ] n (4), [Cd(SCN) 2 (N-phenyltu) 2 ] n (5), [Cd(SCN) 2 (N-2,6-difluorophenyltu) 2 ] n (6), [Cd(SCN) 2 (N, N’-diphenyltu) 2 (H 2 O) 2 ] n (7)[5], [Cd(SCN) 2 (tu) 2 (EtOH) 2 ] n (8), The synthesis has been conduced with an heterogeneous approach, using ammonium and acethate as counter-ions that are lost in the atmosphere to obtain pure products. We characterize these compounds with single crystal X-ray diffraction, (raman and infrared) vibrational spectroscopy, and electronic adsorption and emission spectroscopy. This study allows also to rationalize the luminescent properties of this family and the effects of structural peculiarities, both in inorganic Cadmium thiocyanate framework and in organic ancillary ligands, to the emission properties with the help of computational models based on TD-DFT methods. [1] Zhang, H., Wang, X., Zhang, X., Teo, B.K.,Coord. Chem. Rev., 1999,183,157-195 [2]g, H.u, H., Xiao, W., Zhang, K., Teo, B.K., Inorg. Chem., 1999, 38, 886-892;Zhang, L.P., Lu, W.J., Mak, Chem. Comm., 2003, 2830-2831; Jia, H.L., Jia, M.J., Li, G.H., Wang, Y.N., Yu, J.H., Xu, J.Q., Dalton Trans., 2013, 42, 6429-6439 [3]Nardelli, M., Braibanti, A., Fava, G., Gazz. Chim. Ital., 1957, 87, 1209-1231 [4]Mietlarek-Kropidlowska, A., Chojnacki, J., Acta Cryst.,2012, E68, m1051-m1052 [5]Zhu, H.G., Yang, G., Chen, X.M., Ng, S.W., Acta Cryst., 2000, C56, e430-431 From the structural analysis of this family of compounds emerge the importance of different interactions: 1)The choice of the solvent is essential to direct the synthesis, and from weak difference in hydrogen bonding capability and polarity very different topology can be obtained 2)Strong hydrogen bonds from N-H of thioureas are the main driving force of the crystallization, and the disposition of substituents and the bridging capabilities of tu and SCN is strongly correlated to the maximization of these interactions, eigter with thiocyanate or with intercalated solvent molecules ( This is also clear from the optimized computational model) 3)The pi-pi stacking has a strong influence in presence of aromatic substituents, especially with halide substituents that maximize the quadrupole of the ring. 4)Bulky substituents has a more pronounced effect on topology, reducing the possibilities to have multiple hydrogen bonds and isolating the inorganic framework. The anisotropy of steric hindrance has weaker effects on structure than bulk. This family of compounds shows great luminescent properties, that from computational modeling seem to be strongly influenced by the presence of Cadmium, differently from what is usually reported in literature. Cd(Ac) 2 + 2 (NH 4 )(SCN)+ x tu H2OH2O Ethanol X=1 X=2 Effect of Solvent and hydrogen bonding on topology of unsubstituted tiourea complexes X=2 (1)(2) (3) Effect on the topology of coordination polymers of an asymmetric N- substitution on tu Cd(Ac) 2 + 2 (NH 4 )(SCN)+ x N-Xtu X=phenyl X=2,4-difluorophenyl X=metyl X=2 (4) (5) (6) Effect on the topology of coordination polymers of a bulkier symmetric substitution on tu and effect of solvent interaction Cd(Ac) 2 + 2 (NH 4 )(SCN)+ x N,N’-X 2 tu (X=phenyl) Ethanol H2OH2O X=2 X=1 (8)(9)

2. Emanuele Priola 1 1 University of Turin, Via Pietro Giuria 7, 10125, Italy, e-mail: emanuele.priola@unito.it And considering the properties of twinned solids? W HADHAWAN T ENSORIAL CLASSIFICATION OF TWINS T-twins: No difference in tensor properties B-twins: twins differ in at least one tensor properties, and no prototype structure can be defined Aizu twins: twins differ in at least one tensor properties, and a prototype structure can be defined T HESE TWINS CHANGE THE TENSOR PROPERTIES, THESE ARE THE GOAL FOR AN IMPROVEMENT IN MATERIAL SCIENCE !! Introduction A twin is an oriented association of individual crystals of the same chemical and crystallographic species. The individuals in a twin are related by one or more geometrical laws (twin laws) expressed through the point symmetry of the twin versus the point symmetry of the individual. The twin element (twin center, twin axis, twin plane) is the geometric element about which twin operations (operations relating different individuals) are performed. These definitions allows the classifications of the different cases in the framework of Friedel’ s Reticular theory of twinning, extended in recent years by Nespolo and others [1]. A different, less group theory-based classification, is based on tensor properties of crystals subject of this phenomenon[2]. However, the first classification is important from an abstract definition of twins especially in the framework of polychromatic group theory [3], while the second is important for a more applicative study on this phenomenon. Tensor properties are fundamental for solid state physics: hyperpolarizability, electrical properties and mechanical properties are influenced by structural phenomena that change the components in the different directions. With a rational induction of twinning phenomenon, some peculiar properties in materials have been obtained, especially for metals, and a more comprehensive study in this directions can be significant. This abstract notions can be really important in the frameworks of the research on coordination polymers for more than one reason. At first, a deep knowledge of the group theory based approach to twin allows their recognition and classification when they are found in experimental work. This is essential, because often the unrecognition of this phenomenon cause a poor resolution in structural determination, or wrong space group assignation, or even the impossibility to resolve the structure. This is particularly significant in the case of Coordination polymers: the presence of weak non strongly directed interactions in certain specific directions is a favorable condition for the manifestation of twinning. On the other hand, the possibility to change the properties of solids with a rationally conducted growth of twins is a desirable and intriguing aim. This poster presents some of the instruments that the theory of Geminography give us for a better interpretation and rationalization of this phenomenon with possible developments. [1]Grimmer, H., Nespolo, M., Z. Kristallogr., 2006, 221, 28-58 [2]Wadhawan, V.K., Acta Cryst., 1997, A53, 546-555 [3]Nespolo, M., Z. Kristallogr., 2004, 219, 57-71 D(L T )= holohedral vector point group descrybing the point symmetry of L T. This is the twin lattice, the lattice common to all the individuals of the twin D(L ind )= holohedral vector point group describing the point symmetry of L ind, that is the lattice of the individual D(H)= holohedral supergroup of H H = intersection group of the oriented vector point groups of individuals of twin K= chromatic point group called twin point group, point group that represent in the vector space the symmetry of the twin and is a supergroup of H. OBLIQUITY: lets indicate [u’,v’,w’] the direction perpendicular to (hkl) and (h’,k’,l’) the plane perpendicular to [uvw], where [uvw] and (hkl) are the lattice plane and the lattice row that define the twin. The angle between [uvw] and [u’v’w’] or (hkl) and (h’k’l’) is the obliquity. cosω = (uh + vk + wl)/L(uvw)L*(hkl) TWIN INDEX (molteplicity): ratio of the volumes V t and V of primitive cells for L T and L ind. N UMBER OF TWIN INDIVIDUALS Some little definitions… ω T WIN INDEX (n) O BLIQUITY ( ω ) R ELATIONS AMONG D(L T ), D(L IND ), D(H) AND H Classification of crystal twins based on Friedel Lattice theory n =1 n >1 ω =0 ω >0 ω =0ω >0 1)D(L T )=D(L ind ) D(H) K H S YNGONIC MEROHEDRY 2) D(L T )=D(L ind ) D(H) K H M ETRIC MEROHEDRY 1)D(L T ) D(L ind ) P SEUDOMEROHEDRY 1)D(L T ) ≠ D(L ind ) R ETICULAR MEROHEDRY 2)D(L T ) = D(L ind ) R ETICULAR POLYHOLOHEDRY 1)D(L T ) ≠ D(L ind ) R ETICULAR PSEUDOMEROHEDRY 2)D(L T ) = D(L ind ) R ETICULAR PSEUDOPOLYHOLOHED RY T HE MOST FREQUENT IN C OORDINATION POLYMERS !! But what is the group K? A deeper classification on the basis of polichromatic symmetry  the color). Chromatic symmetry operation (twin law), that generate one individual from the other. Chromatic point group, supergroup of the intersection group with a left coset decomposition generated with the chromatic symmetry operation. Point group symmetry of individuals Chromatic symmetry operation : symmetry operations that exchange the colors of the squares. Each individual is a different colored series of squares and maintain only the symmetry elements that doesn’t change the color Chromatic point group is the group that formed by the “sum” of the symmetries that maintains the colors and of those that change the color with a comma to distinguish them {1120} Brazil Twin of alfa Quartz, a twin for syngonic merohedry T HIS SHORT NOTATION COMPREHENDS ALL THE INFORMATION ABOUT THE TWIN CONSIDERED !! C ONCLUSIONS In this contribution, we show a classification of the more frequent typologies of twins for such a low symmetry compounds like Coordination polymers. Moreover, we would like to suggest a greater use of the short notation of chromatic groups for this phenomenon. This expansion of symmetry groups is not only thought for n=2 twins, like dichromatic Shubnikov groups [4], but is more general, and in its systematic all the information about the overall symmetry of the twin can be obtained. Moreover, we want to suggest a more systematic study on the rational crystal growth of Bollmann and Aizu twins for their enormous possibility to change the properties with a tensor nature, not only essential in the field of coordination polymers, but for all the material science. [4]Shubnikov, A.V., Koptsik, V.A., Symmetry in Science and Art. New York, London; Plenum Press, 1974