Hydrogen-bonded networks from copper(II) carboxylate dimers
What is it about?
The work centers on the use of 4-hydroxybenzoate anion (Hhba‾) and its deprotonated phenolate form 4-oxidobenzoate (hba 2‾) to obtain complexes with the general formula [Cu 2 (Hhba) 4-x (hba) x L 2-y ] x‾ , where L is an axial coligand. The study focuses on the formation of extended networks through hydrogen bonding and coordinate bonds when bridging coligands are employed. The main compounds reported are crystals of [Cu 2 (Hhba) 4 (dioxane) 2 ]·4(dioxane), [Cu 2 (Hhba) 4 (H 2 O) 2 ]·2(Et 4 NNO 3 ), [Cu 2 (Hhba) 4 (O-bipy)]·H 2 O, and [Cu 2 (Hhba) 4 (O-bipy) 2 ]·2(dioxane). The synthesis of these compounds involves adding H 2 hba to Cu 2 (OAc) 4 ·2H 2 O, followed by the addition of L in a 1:4 ratio in 1,4-dioxane. The structures of these compounds have been reported previously in the Cambridge Structural Database (CSD).
Why is it important?
This research is important because it highlights the potential of copper dimers in generating a range of extended crystalline structures through hydrogen bonding. Understanding the different ways that hydrogen bonding can create networks and connect nodes in these structures is crucial for the design and synthesis of new materials with tailored properties. Key Takeaways: 1. The research explores the formation of copper dimer complexes incorporating the 4-hydroxybenzoate anion (Hhba‾ ) and its deprotonated phenolate form 4-oxidobenzoate (hba 2‾). 2. Various extended networks are generated through hydrogen bonding, with some crystals also including coordinate bonds when bridging coligands (L) are employed. 3. Different hydrogen-bonding motifs can serve as 4-connecting nodes in these networks, such as planar zigzag motifs and a motif involving three phenol groups serving as donors to a single phenolate group. 4. Hydrogen bonding plays a key structural role in the arrangement of molecular components in the copper dimer complexes, although not all structures contain hydrogen-bonded nodes within networks. 5. The study demonstrates the potential for creating a wide variety of extended structures by exploiting the ability of phenolic/phenolate groups within Cu II tetracarboxylate dimers and using different countercations for crystal engineering.