Recent Developments in Synthesis and Applications of Triptycene and Pentiptycene Derivatives

Abstract

Iptycenes are a class of aromatic compounds with arene units fused to the [2.2.2]bicyclooctatriene bridgehead system. As a result of their unique structures, more and more iptycenes, especially triptycene and pentiptycene derivatives, have been efficiently synthesized. These compounds have wide applications in many research areas, including molecular machines, molecular balances, catalysis, materials chemistry, molecular assembly, host–guest chemistry, and so on. This microreview mainly describes the developments in the synthesis and applications of triptycene and pentiptycene derivatives during the last ten years. Particular attention is paid to the synthesis and applications of hosts derived from triptycene and pentiptycene systems in recent years.

Pentiptycene-based polyimides with hierarchically controlled molecular cavity architecture for efficient membrane gas separation

“…As shown in Table 3, although the change of fractional free volume as a function of substituent groups followed the same trend in these two series of polymers (i.e., -CF 3 > -H > -CH 3 Figure 5) allows the CF 3 groups to fill in this volume at least in part, which counteracts the effect of chain packing disruption of CF 3 groups leading to a less significant increase of the overall FFV (by 7.6%) for pentiptycene-based polyimide. The observed difference in volume change supports that our previously proposed "partially filling" mechanism which may be readily generalized to other iptycene-containing polymers Gas permeability and ideal selectivity of pentiptycene 19 containing polymers. The observed difference in volume change supports that our previously proposed "partially filling" mechanism which may be readily generalized to other iptycene-containing polymers Gas permeability and ideal selectivity of pentiptycene 19 containing polymers.…”

“…[15] Triptycene is a three-dimensional symmetric, bulky and rigid molecule composed of three benzene "blades" in paddlewheel-like configuration (Figure 1a). [19,20] Its three-dimensional structure is shown in Figure 1b. [6,[15][16][17][18] As demonstrated in our previous paper on triptycene-polyimide membranes, [15] a unique and appealing feature of this simplest iptycene molecule is that the open space between the benzene rings, called "internal free volume", not only introduces significant amount of "intrinsic" free volume into the polymer for fast transport, but also provides a feasible means to finely tune the size of internal free volume or molecular cavity by varying the substituent groups neighboring the triptycene units.…”

Triptycene‐Based Chiral and meso‐N‐Heterocyclic Carbene Ligands and Metal Complexes

“…The rigid geometry of the bulky triptycene unit should enable the deep penetration of the space close to a catalytically active metal, prevent the M−C(NHC) rotation, and thus, may enable stereoselective catalysis (Scheme ). For such ligands an efficient gearing mechanism based on the C 3 ‐symmetric triptycene is likely . Steric bulk at the imidazole ring acts on one triptycene wing, orienting the second one, and shielding the space close to the metal to enable steric control at the metal center.…”

Tris(tetraceno)triquinacenes: Synthesis and Photophysical Properties of Threefold Linearly Extended Tribenzotriquinacenes

“…21 Different from triptycenes bearing three acene wings oriented perpendicular to a common plane and mutually at 120 °,22 TBTQ‐based acenes would stretch out into the three‐dimensional space at about 90 ° to each other, with obvious consequences for the so‐called internal free volume (IFV) generated 22. 23…”

“…[20,21] Different from triptycenes bearing three acene wings oriented perpendicular to a common plane and mutually at 120 8, [22] TBTQ-based acenes would stretch out into the three-dimensional space at about 90 8 to each other, with obvious consequences for the so-called internal free volume (IFV) generated. [22,23] Whereas various successful directed extensions of the three aromatic wings of the TBTQ system have been reported, [17,18,[24][25][26][27] threefold (''linear'') extension with acene units has not been achieved yet. By contrast, single-wing extension was feasible by Diels-Alder methodology involving in situ-generated TBTQ-based monoaryne and monoisobenzofuran analogues at low temperature for trapping with vari-Keywords: acenes · photophysics · polycyclic compounds · quinones · UV/Vis spectroscopy Abstract: The linear extension of the rigid, C 3v -symmetrical carbon framework of tribenzotriquinacene (TBTQ) along its three wings is reported.…”