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Electronic absorption and emission spectra as well as He(I) photoelectron spectra of 2,2,4,4-tetramethyl-1,3-cyclobutanedithione and 2,2,4,4-tetramethyl-1-3-thio-1,3-cyclobutanedione have been interpreted on the basis of molecular orbital calculations. The results show that the non-bonded orbital of the dithione is split owing to through-bond interaction, the magnitude of splitting being 0.4 eV. The π* orbital of the dithione appears to be split by about 0.2 eV. Electronic absorption spectra show evidence for the existence of four n—π* transitions, arising out of the splitting of the orbitals referred to above, just as in the case of 2,2,4,4-tetramethyl-1,3-cyclobutanedione. Electronic and photoelectron spectra of the thio-dione show evidence for weak interaction between the CS and C&.zdbnd;O groups, probably via π* orbitals. Infrared spectra of both the dithione and the thio-dione are consistent with the planar cyclobutane ring; the ring-puckering frequency responsible for non-bonded interactions is around 67 cm−1 in both the dithione and the thio-dione, the value not being very different from that in the dione. The 1,3-transannular distance is also similar in the three molecules.

Two new open-framework zinc oxalates have been prepared by hydrothermal methods in the presence of structure-directing organic amines. The crystal data for these oxalates are as follows: I, [H3N(CH2)3NH3]2+[Zn2(C2O4)3]2-·3H2O, triclinic, space group P1̄ (no. 2), a = 9.261(1) Å, b = 9.455(1) Å, c = 12.487(1), α = 83.93(1)°, β = 88.01(1)°, γ = 61.03(1)°, V = 951.1(1) Å3, Z = 2, M = 524.8, Dcalc = 1.83 g cm-3, μ = 2.60 mm-1, Mo Kα, RF = 0.03; II, 2[C3H7NH3]+[Zn2(C2O4)3]2-·3H2O, monoclinic, space group C2/c (no. 15), a = 15.847(1) Å, b = 9.685(1) Å, c = 18.333(1), β = 115.5(1)°, V = 2539.1(2) Å3, Z = 4, M = 569.1, Dcalc = 1.60 g cm-3, μ = 1.97 mm-1, Mo Kα, RF = 0.07. In I, the linkages between the Zn and oxalate units gives rise to a layered architecture with 12-membered (6 Zn and 6 oxalates) honeycomb-like apertures wherein the amine and water molecules are located. In II, the Zn−oxalate layers are cross-linked by another oxalate unit giving rise to a three-dimensional structure with two distinct channels where the amine and water molecules reside; the largest aperture in II involves a 20-membered ring (10 Zn and 10 oxalates). There is extensive hydrogen bonding among the amine, water, and the framework. Adsorption studies indicate that water can be reversibly adsorbed in I.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

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Mechanical properties of single-walled carbon nanohorns (SWNH) and SWNH plus few-layer graphene (EG)-reinforced poly(vinyl alcohol) (PVA) matrix composites have been measured using the nanoindentation technique. The elastic modulus (E) and hardness (H) of PVA were found to improve by ∼315% and ∼135%, respectively, upon the addition of just 0.4 wt % SWNH. These properties were found to be comparable to those obtained upon the addition of 0.2 wt % single-walled nanotubes (SWNT) to PVA. Furthermore, upon binary addition of 0.2 wt % EG and 0.4 wt % SWNH to PVA, benefits in the form of ∼400% and ∼330% synergy in E and H, respectively, were observed, along with an increased resistance to viscoelastic deformation. The reasons for these improvements are discussed in terms of the dimensionality of nanocarbon, the effectiveness of nanocarbon and polymer matrix interaction, and the influence of nanocarbon on the degree of crystallinity of the polymer. The results from SWNH reinforcement in this study demonstrate the scope for a novel and, in contrast to SWNT composites, a commercially feasible opportunity for strengthening polymer matrices.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTA novel iron fullerene (FeC60) adduct in the solid stateT. Pradeep, G. U. Kulkarni, K. R. Kannan, T. N. Guru Row, and C. N. R. RaoCite this: J. Am. Chem. Soc. 1992, 114, 6, 2272–2273Publication Date (Print):March 1, 1992Publication History Published online1 May 2002Published inissue 1 March 1992https://pubs.acs.org/doi/10.1021/ja00032a059https://doi.org/10.1021/ja00032a059research-articleACS PublicationsRequest reuse permissionsArticle Views340Altmetric-Citations64LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-AlertscloseSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts

No abstract is provided for this article.