Av apor-induced cyclization has been observed in the host environment of ac rystalline molecular flask (CMF), within which 1,8-bis(2-phenylethynyl)naphthalene (bpen), ad iarenynyl system primed for cyclization, was exposed to iodine vapor to yield the corresponding indeno[2,1-a]phenalene species.T he cyclization process,u nique in its vaporinduced, solvent-free nature,w as followed spectroscopically, and found to occur concurrently with the displacement of lattice solvent for molecular iodine in CMF·0.75 bpen·2.25 CHCl 3 ·H 2 O. The cyclization occurred under mild conditions and without the need to suspend the crystals in solvent. The ability of CMFs to host purely gasinduced reactions is further highlighted by the subsequent sequential oxidation reaction of cyclized 7-iodo-12-phenylindeno[2,1-a]phenalene (ipp) with molecular oxygen derived from air,yielding 12-hydroxy-7-iodo-2-phenylindeno-The advent of crystalline molecular flasks [1,2] (CMFs) has provided abreakthrough in the crystallographic visualization of chemical processes and species. [3,4] This stems from the ability of the flexible coordination polymer in question, which is derived from 2,4,6-tris(4-pyridyl)-1,3,5-triazine (tpt) linkers and zinc halide nodes,t os well and contract upon solvent addition and loss, [5] and undergo guest exchange in as inglecrystal-to-single-crystal manner.[6] Tw os trategies have been employed within CMF chemistry that employ either p-p interactions [7] or complementary pore-guest sizes and shapes to localize guest molecules.T he former strategy allows am odular approach to be employed by modifying the planar aromatic handle. [8] This provides an anchor for postsynthetic modification (PSM) reactions that occur in the solid state and can be monitored crystallographically. [9][10][11][12][13][14][15] In the absence of an aromatic handle,m atching of the spatial dimension of the pore cavity is also av iable strategy to observe guests using crystallographic methods.This approach has been used to probe photoswitching, [16] change conformational isomerization ratios, [17,18] observe unusual molecular interactions, [19] and identify organic species, [20,21] with the notable advantage of requiring only nanogram to microgram quantities of the analyte.[3]Arange of chemical reactions have been observed within CMFs,i ncluding the conversion of amines into imines, [9,10] Huisgen cycloadditions, [11] Diels-Alder reactions, [14] and metal-catalyzed methylation [12] and bromination.[15] All of these processes occurred upon immersing aC MF that contained am odified intercalated triphenylene moiety into solutions with appropriate chemical reactants.O nly one example of achemical reaction combining gas-phase reagents and aCMF has been reported, and involved the conversion of avinyl group into epoxidation/oxidation products with the aid of ar adical initiator. [14] This reaction, however,r equired loading of the CMF with 2,2'-azobis(isobutyronitrile) and the use of forcing conditions,whereby an emulsion of crystals was heated at 8...
