Syntheses, structures, and spectroscopy of mono- and polynuclear lanthanide complexes containing 4-acyl-pyrazolones and diphosphineoxide Fabio Marchetti a,⇑ , Claudio Pettinari a,⇑⇑ , Adriano Pizzabiocca a , Andrei A. Drozdov b , Sergei I. Troyanov b , Constantine O. Zhuravlev c , Sergey N. Semenov d , Yuriy A. Belousov e , Ivan G. Timokhin a a Dipartimento di Scienze Chimiche, Università degli Studi, via S. Agostino 1, 62032 Camerino, Italy b Moscow State University, Chemistry Department, Vorobjevy Gory, 119991 Moscow, Russia c Institute of Radioengineering and Electronics of RAS, 11 Mokhovaya Street, 103907 Moscow, Russia d Department of Inorganic Chemistry, University of Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland e Moscow State University, Department of Materials Sciences , Vorobjevy Gory, 119899 Moscow, Russia article info Article history: Received 12 May 2010 Received in revised form 27 July 2010 Accepted 3 August 2010 Available online 7 August 2010 Keywords: X-ray crystal structures Luminescence Lanthanide compounds Acylpyrazolones Diphosphineoxides abstract Lanthanide coordination compounds are important due to their unique luminescence and magnetic properties. Direct synthesis of oligo- and polymeric Ln complexes with a predicted structure is hampered due to high coordination numbers and unstable coordination polyhedra. A «building blocks» strategy for the synthesis of Ln(Q) 3 L polymers (Ln = Eu, Tb or Gd; HQ = 1-phenyl-3-methyl-4-RC(@O)pyrazol-5-one in general, in detail HQ S , R = thienyl; HQ CP : R = cyclopentyl; L = bis(diphenylphosphine)methane dioxide dppMO 2 , bis(diphenylphosphine)ethane dioxide dppEO 2 , and bis(diphenylphosphine)butane dioxide dppBO 2 ) has been used: {Ln(Q) 3 } mononuclear fragments have been linked by dppXO 2 bridges when X = E or B, while monomeric molecular derivatives have been isolated with dppMO 2 . Eighteen new complexes were prepared, 12 of them showing a polymeric nature and 6 being monomers. Three compounds have been structurally characterized, further confirming the hypothesized connectivity where metal centers have been found to exist in LnO 8 square antiprismatic environments. Luminescence properties have been also investigated. Ó 2010 Elsevier B.V. All rights reserved. 1. Introduction In the recent years an increasing attention has been devoted to the design and production of coordination polymers (CPs) of lan- thanides with different networks [1–3]. Lanthanide-containing systems often exhibit intense luminescence and are potentially interesting for the design of luminescent materials and devices. Due to their high coordination number and special magnetic and fluorescence properties [4], the lanthanide ions are likely to pro- vide new CPs materials that possess specific properties and desired features, as molecular magnets [5], luminescent devices [6], cata- lysts [7], molecular sieves [8], sensors for molecular recognition [9], and ion exchange [10]. The lanthanide complexes, being predominantly ionic and pos- sessing high lability in solution, usually have different coordination environment on the metal ion. Even by using a unique kind of ligand, compounds with different coordination numbers can be easily prepared. However, it prevents the formation of the regular polymeric structure. One way to avoid this problem is to employ structurally rigid secondary building blocks (SBUs) with predeter- mined geometries and coordination abilities towards linking groups. Among our research on lanthanide chemistry with the family of 4-acylpyrazol-5-ones [11] we have found an interesting tetraden- tate ligand H 2 Q 2 Q, with two 4-acylpyrazole-5-one moieties linked by two methylene groups (CH 2 CH 2 ), that has been recently showed to form dimeric complexes with lanthanide ions, that have proven to be used as suitable rigid SBUs (secondary building units) in the construction of regular polymeric assemblies [12]. In fact, each Ln atom in such Ln 2 (Q 2 Q) 3 L 2 dimers is heptacoordinated by three chelating acylpyrazolonate groups and one donor atom from the additional neutral ligand L (L is for example water or dmf or triphe- nylphosphineoxide), and the substitution of L by ditopic ligands re- tains the rigid structure of the {Ln 2 (Q 2 Q) 3 } fragment, which can be used as starting material for the construction of infinite helical chains bridged, for example, by diphosphine dioxide ligands [12]. Here we report the results concerning the interaction between a family of diphosphineoxide ligands dppXO 2 with a different number of bridging methylene groups (dppXO 2 = Ph 2 P(@O)- (CH 2 ) n P(@O)Ph 2 in general, in detail: dppMO 2 , n = 1; dppEO 2 , n = 2; dppBO 2 , n = 4) and tris-complexes of lanthanides Ln (Ln = Eu, 0020-1693/$ - see front matter Ó 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.ica.2010.08.006 ⇑ Corresponding author. Tel.: +39 737 402217; fax: +39 737 637345. ⇑⇑ Corresponding author. Tel.: +39 737 402217; fax: +39 737 637345. E-mail address: fabio.marchetti@unicam.it (F. Marchetti). Inorganica Chimica Acta 363 (2010) 4038–4047 Contents lists available at ScienceDirect Inorganica Chimica Acta journal homepage: www.elsevier.com/locate/ica