Crystal Engineering

Effects of Wet-Pressing and Cross-Linking on the Tensile Properties of Carbon Nanotube Fibers

“…In this experiment, the liquid (AAD) had two functions: as a capillary-pressure inducer and as a crosslinker. CNTFs can be strengthened by capillary densification [12,14] or cross-linking methods [15,16,17,18,19,20,21,22,23]. However, the liquid cannot smoothly infiltrate the CNTF [18] (Figure 1b top), because CNTs are generally insoluble and difficult to disperse [31].…”

“…The vdW force (2–10 kJ/mol) acts between CNTs, but is relatively weak compared to covalent bonds (150–500 kJ/mol) [19]. Therefore, a method to introduce covalent bonds between the CNTs was attempted using the 1-step Friedel-Craft reaction (Figure 1c) with AAD.…”

“…Physical approaches that have been tested include torsion [12,13,14], tension [15,16,17,18], and capillary densification [12,14]. Chemical approaches exploit strong covalent bonds (125–500 kJ/mol) between the CNTs [19]. Methods include cross-linking using diazonium salt [20,21,22], radical reactions [23,24,25], [2+1] cycloaddition [26], esterification [27], and plasma treatment [28].…”

Organic crystal engineering beyond the Pauling hydrogen bond

“…This article describes some of the alternative weaker attractions and how they influence crystal packing in an applied manner. 6 Our knowledge of this area lags behind the stronger force approach and therefore its characteristics and limitations will also be addressed.…”

Halogen containing clusters N2Br2, N2Br4, S2Br4and S2Br6yield penannular inclusion compounds

“…In his comprehensive account of crystalline molecular compounds, Herbstein has estimated that around 90% of two component materials were first obtained by chance. 1 A significant synthetic challenge in crystal engineering 2,3 is therefore the design of new molecules that will function as inclusion hosts. 4,5 This is especially so for molecular combinations that employ only interactions that are weaker and less directional than Pauling-type hydrogen bonding.…”