A series of microporous coordination polymers of adipic (H 2 ad) and pimelic acids (H 2 pim) with rare earth metals have been synthesized and structurally characterized. In the case of adipic acid, two distinct structure types were isolated: structure type I with formula [Ln 2 -(ad) 3 (H 2 O) 4 ]6H 2 O, Ln ) Ce 3+ , Pr 3+ , Nd 3+ , and strucure type II with formula [Ln 2 (ad) 3 (H 2 O) 4 ]-xH 2 O, Ln ) Nd 3+ , Sm 3+ , Gd 3+ , Er 3+ , Yb 3+ . Type I compounds are isostructural to lanthanum adipate (Inorg. Chem. 1998, 37, 3407) and contain interconnected channels filled with hydrogen-bonded water molecules. The structure of type II polymers consists of interpenetrated (4,4) metal-organic networks. Channels along one crystallographic direction are created by the interpenetration. The minimum width of the channels depends on the nature of the metal incorporated in the framework. The passage from type I to type II structure is ascribed to the well-known effect of lanthanide contraction. In the case of H 2 pim, one compound of formula [La(pim)(Hpim)(H 2 O)]H 2 O was isolated. Channels, filled with water molecules, are formed along one crystallographic direction. In all compounds, the water molecules can be reversibly removed.

This study explores the effectiveness of a cooperative learning (CL) approach, where students work together and elaborate concepts of physics. The group problem‐solving tasks were conceptual questions from physics, where the students had to discuss and provide explanations of some phenomena. The effectiveness of the learning‐in‐groups approach was validated and correlated with working group interactiveness. Two group variables were assigned: the group performance and the group activity. These variables and the subjects' participation variable were correlated with achievement. Discourse analysis revealed variation in the nature of the interactions and information exchange, and the two roles as learners and learning facilitators. In addition, the study provided evidence for some features of cooperative learning that could characterize it as a nonlinear dynamical process. Implications of the findings are discussed. © 2006 Wiley Periodicals, Inc. J Res Sci Teach 43: 556–576, 2006

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