π-acidic Naphthalene Diimides: Syntheses, Structures, Spectral And Catalytic Properties

Naphthalene diimide(NDI)is an attractive class of electron-deficient organic dyes since their potential applications in molecular recognition and sensing,anion transport,organic field-effect transistor,biological medicine and molecular catalysis.Among these applications,most of them are related to the electron-deficience(π-acidity)of π-systems in NDIs.It is known that the latter can be tuned by the introduction of substituents at the imide and naphthalene-core-peripheral positions(core-substituted NDIs also named as cNDIs)of NDIs,where the substituents at two imides mainly affect the solubility and molecular packing in solid state of NDIs,while those at naphthalene-core-peripheral positions can modulate the electronic structures(electronic absorption spectra)and thusπ-acidity of NDIs.Furthermore,in the solid state,the molecular packing of NDIs and guest molecules will also influence on their electronic structures(electronic absorption spectra)and π-acidity.To get an insight into the structure-property relationships of such π-acidic NDIs,a series of novel NDIs bearing different substituents have been synthesized and characterized in this thesis,and their crystal structures and spectral properties have been investigated.Moreover,the impact of the aggregation of NDIs and guest molecules on their electronic absorption spectra have also be examined.Based on these,several suitable NDIs have been sorted out for their catalytic studies.For details,please see the followings:1.From the starting materials naphthalene tetracarboxylic dianhydride,5 core-unsubstituted NDIs that contain the different steric and functional substituents at imide positions,as well as 12 cNDIs that bear the different substituents at naphthalene-core-peripheral positions have been designed and synthesized.Furthermore,5 co-crystals of NDIs have been prepared by the co-crystallizations.All the obtained intermediates and products have been characterized by the NMR,MS and X-ray single-crystal structural technique.2.The photophysical and photochemical properties of all the obtained NDIs have been carefully studied.First of all,the effect of substituents(the electron-donating as well as steric hindrance)of NDIs on their spectral properties had been checked and discussed.Secondly,the influences of the aggregation of NDIs and guest molecules on their electronic absorption spectra have be studied through a crystal-engneering strategy.3.The catalytic properties of several selected NDIs have been preliminarily explored.Firstly,a π-acid electron-transfer organocatalyst based on NDIs had been developed for ambient oxidative C-C coupling of 2,6-di-tert-butylphenol to its dimeric derivative or unexpected ring-rearranged trimeric quinone methide product by controlling reaction temperatures.However,together with radical TEMPO,such organocatalyst are found to promote the ambient oxidation of 2,6-di-tert-butylphenol to its monomeric quinine product directly.Secondly,due to a strong electron donor-acceptor interaction between NDIs and a precursor for the pillararene,1,4-diisobutoxy-2,5-bis(methoxymethyl)benzene,NDIs has been demonstrated to act as a template for selective synthesis of pillar[6]arene in a modest yield.