Coordination environments and π-conjugation in dense lithium coordination polymers

Abstract

Understanding of lithium oxygen coordination systems is important for making better lithium conductors as well as active materials for lithium ion batteries. Here we report a systematic investigation on coordination environments in lithium coordination polymers (LCPs) through the syntheses and analyses of six new crystals composed of lithium ions and anthraquinone (aq) derivative anions, where the negative charges are distributed in π-conjugation systems. Their structures were determined by single-crystal X-ray diffraction as (1) 1 2 1 2 1 , and (6) [Li(14hnaq)(H 2 O)] in P2 1 2 1 2 1 (23dcaq 2-= 2,3-dicarboxy-aq, 14dhaq 2-= 1,4-dihydroxy-aq, 15dhaq 2-= 1,5dihydroxy-aq and 14hnaq -= 1-hydroxy-4-nitro-aq). Through the comprehensive structure analysis of these materials as well as other LCPs, we found that when considering the longest C-O bond in the π-conjugation system of an anionic organic molecule and its coordination to a Li ion, there is a weak inverse relationship between the C-O and Li-O bond length. In addition, despite exhibiting optical band edges below 2 eV and 1-D π-stacking connectivity, conductivity measurements on single crystals of 1-6 confirmed that they are all electronic insulators. We rationalize this finding on the basis of π-orbital delocalization, which is more restricted in the aq-based LCPs compared to known semiconducting hybrid materials.

Lithium Aryloxide Thin Films with Guest‐Induced Structural Transformation by ALD/MLD

“…The Li−O bond lengths (1.90–1.94 Å) are very close to those reported for structurally similar lithium phenolate cubane clusters (1.91–1.98 Å) . Also, the C−O lengths are essentially equal in the two structures (1.34 and 1.33 Å for Li 2 Q and Li‐phenolate, respectively), which implies charge localization on the oxygen atom of equal magnitude . Compared to the experimental data, the calculated diffraction pattern matches very closely to the experimental one (Figure a) and Le Bail fitting (Figure S5 in the Supporting Information) in space group Pccn yields an excellent fit with lattice parameters very close to the predicted values: a= 11.25 Å, b= 10.45 Å, c= 4.66 Å.…”

“…[30] Also, the CÀOl engths are essentially equal in the two structures( 1.34 and 1.33 for Li 2 Qa nd Li-phenolate, respectively), [30] which implies charge localization on the oxygen atom of equal magnitude. [31] Compared to the experimental data, the calculated diffractionp attern matches very closely to the experimentalo ne (Figure 2a )a nd Le Bail fitting ( Figure S5 in the Supporting Information) in space group Pccn yields an excellent fit with lattice parameters very close to the predicted values: a = 11.25 , b = 10.45 , c = 4.66 .T he original tetragonal structure isotypic to Na 2 Qw as also evaluated, but this resulted in amarkedlyp oorer fit ( Figure S6). Figure 2bshows furtherv alidation of the structure as the theoretical IR spectrum produces all the IR absorption bands that appear in the experimental spectrum( full interpretation of the vibrational modes in Ta bleS2inthe Supporting Information).…”

Hidden negative linear compressibility in lithiuml-tartrate

“…Nevertheless, the mechanical behaviour of 1 seems to be reliant on the flexibility of the closed-shell Li coordination sphere, which we previously reported could be easily manipulated by both chemical and mechanical means. 24,25 It is interesting to compare the recent findings of NLC in LnFe(CN)6 compounds and Co(II) citrate, which originate directly from flexibility in the Ln(III) and Co(II) environments, respectively, rather than from any common topological mechanism. 26 In the tartaric acid ligands, we observe large changes in torsion angles between the carboxylate oxygen atoms and the ligand carbon backbone, φO-C-C-C (Figure 3e).…”

Metal–Organic Frameworks Constructed from Group 1 Metals (Li, Na) and Silicon-Centered Linkers

“…10 Since then, Li + -based MOFs have been reported using linkers as varied as amino acids, thiophenedicarboxylates, and anthraquinones. [11][12][13][14][15][16] These Li + -based MOFs have been shown to display properties such as luminescence, [17][18][19] gas uptake, [20][21] and even have potential applications as electrodes in Li batteries. 13 Some Na + -based MOFs have also been reported to possess similar properties to their Li + analogs such as gas sorption, luminescence, and anodes for Na batteries.…”