Lee-Gin Lin

Time‐Evolving Self‐Organization and Autonomous Structural Adaptation of Cobalt(II)–Organic Framework Materials with scu and pts Nets

Self-organization is a process, in which an internal system spontaneously opens a new route to increase system complexity without being guided by an external source. The concept of self-organization is central to the understanding of living organisms, biominerals, and new supramolecular materials. For chemistry, self-organizing equilibrium conditions can be controlled by changing a few critical factors (concentration, template, pH, temperature, solvent system, etc.) to generate desirable compounds. However, these explorations seem not to be completely applied in a few particular supramolecular systems. Inspired by biology, to construct a high-order architecture from individual building components, various driving forces may competitively predominate at certain stages of the self-assembly process. A subtle thermodynamic/kinetic balance may control and tune the materials growth delicately. Namely, self-organization processes can be operative if the building components are sufficient and in close proximity, under suitable conditions. If the supply of building units is depleted or reduced, the original equilibrium conditions will change, and a new self-organization process will take place. These intriguing phenomena of self-organization are triggered by an internal stimulus and seem to be easily understood in biology, but the phenomena has not been addressed in the synthesis system of metal–organic framework (MOF) materials. As part of our ongoing efforts in the design and synthesis of functional crystalline materials, we report herein on an intriguing supramolecular system that involves a distinct self-organization process, in which the product structures adapt to autonomous dynamic changes in the ratio of build-

p-triallylcalix[4]arene: The final member of the p-allylcalix[4]arenes

Abstract The heat-induced Claisen rearrangement of calix[4]arene triallyl ether 6a produced the title compound, p -triallylcalix[4]arene (7). The triallyl ether 6a was prepared from calix[4]arene 1,3-diallyl ether ( 1a ) in a three-step process. Benzoylation of 1,3-diallyl ether 1a , under separate reaction conditions, resulted in the formation of either one of the isomeric pair of monobenzoates 2 or 3a . The allylation of 3a and subsequent debenzoylation yielded calix[4]arene triallyl ether 6a . The synthesis and structural assignment of these calix[4]arene derivatives are discussed. Further study of this four-step conversion for other calix[4]arene trialkyl ether derivatives is also presented.

Diallylbis(arylazo)calix[4]arenes: the syntheses of calix[4]arenes with two different para-substituents

The diazonium coupling between two kinds of p-diallylcalix[4]arenes (3 and 4) and p-substituted benzenediazonium salts yielded calix[4]arenes with two different substituents on their para-position. The synthesis and the 1H-NMR spectral characteristic features of the two p-diallylcalix[4]arenes and their arylazo derivatives are discussed.

Calix[4]quinone. Part 1: Synthesis of 5-hydroxycalix[4]arene by calix[4]quinone monoketal route

Abstract The oxidation of calix[4]arene tribenzoate 1 with chlorine dioxide yielded the corresponding calix[4]monoquinone tribenzoate 2. Reaction of monoquinone 2 with ethylene glycol under acidic conditions produced the protected monoketal derivative 3. The basic hydrolysis of the benzoate, followed by an acidic cleavage of ketal moieties and a metal hydride reduction of the quinones or vice versa, converted 3 to the title compound, 5-hydroxycalix[4]arene (7).

Calix[4]quinone. Part 2: Intramolecular Michael-addition of calix[4]diquinone

Abstract The oxidation of calix[4]arene dibenzoate 1 with chlorine dioxide yielded the corresponding calix[4]diquinone 2 and an intramolecular Michael-addition product 3 . Reaction of diquinone 2 with ethylene glycol under acidic conditions produced the half-protected ketal derivative 4 . The removal of benzoate moieties from compound 4 in basic conditions produced a phenoxide anion, which underwent intramolecular Michael-addition and yielded product 5 . In acidic ketal cleavage conditions, the ketal moieties of product 5 were removed, but the intramolecular Michael-addition structure was maintained in the product 6 .