The Synthesis Of Y-shape Photoresponsive Molecules And Their Applications In Anion Sensing And Self-assembly Superhydrophobic Surface

Photoresponsive molecules and their self-assembly structures with novel properties have been attracted much attentions in the past decades,which demonstrated various potential applications in photo-engineering materials,photosensor,molecular recognition and supramolecular materials,etc.As a kind of typical photoresponsive organic molecule,azobenzene and its derivatives have been widely applied in many fields,such as liquid crystal,nonlinear optics,optical storage,holographic grating and photo-controlled devices.Meanwhile,the adhesion behaviors of superhydrophobic surface have attracted great attention in the field of materials engineering.In this thesis,we have designed and synthesized two kinds of Y-shape azobenzene derivatives BNB-Y8 and AOB-Y8 with amide groups and 1,3,4-oxadiazole groups,respectively.The photophysical properties,self-assembly behavior,anionic response behavior and controlled adhesion behavior of superhydrophobic surface have been systematically investigated,and their scientific mechanisms in ion recognition and controlled adhesion behaviors have been analyzed and revealed..The details can be listed as follows:1.Azobenzene derivative BNB-Y8 with bis-amide and AOB-Y8 with oxadiazolyl groups have been synthesized.The element analysis and structure characterization of these two molecules have been performed by using ¹H NMR spectra,FT-IR spectra and elemental analysis.The obtained results confirm the successful systhesis of these two kinds of compounds.2.The Y-shape azobenzene derivatives BNB-Y8 and AOB-Y8 have good photoresponsivity in solution.It was found that the BNB-Y8 and BNB-Y8-F^-complexes in chloroform irradiated with 365 nm UV light produces a marked difference in fluorescence.The combination with F^-can accelerate BNB–Y8response rate of UV light.Similarly,when AOB-Y8 50:50 chloroform-acetonitrile mixed solvent(1 mg mL^-1)was irradiated with UV light,the obvious change in the UV-Vis absorption spectrum indicates that the occurrence of trans-cis isomerisation,and the isomerization rate can be up to 85%.With the photo-induced isomerization of AOB-Y8 from-trans to-cis,the morphology of surface changes from root-like flower nanometer arrays to spherical particle,and then to lamellar,meanwhile the surface wettability also changes from superhydrophobic to hydrophobic,and then to hydrophilic.The UV induced intermolecular interaction forces is the main reason for the change of surface self-assembly and wettability.3.The self-assembly behavior of Y-shape azobenzene derivatives BNB-Y8 have been systematically investigated.The mechanism for the formation of gel can be attributed to the synergy of intermolecular hydrogen bond,azobenzene?-?stacking and van der Waals force via the alkyl chain,which has been proved by gel ability test,gel-sol phase transition temperature and spectroscopy studies.The anion response behaviours study of the compound BNB-Y8 demonstrates a double-responsive to F^-,which can be demonstrated from the spectral changes and by“naked-eye”in solution and gel-sol phase transition in the gel phase.And the selectivity of BNB-Y8 to anions can be effectively regulated by changing the solvent.The colorimetric sensing property of BNB-Y8 in sensing F^-can be completely recycled upon the addition of H⁺,as a result,this switchable property of BNB-Y8 can be used as an OFF-ON-OFF reversible colorimetric sensor.4.The microstructure,wettability and adhesion properties of AOB-Y8 self-assembled surface through changing the composition of chloroform-acetonitrile?CHCl₃-CH₃CN?mixed solvents,concentration,temperature and light illumination have been systematically investigated.With the increase of CH₃CN content,the morphology of surface changes from root-like fibres to flower nanometer arrays,and then to short sticks,meanwhile the surface wettability also changes from hydrophobic to superhydrophobic,and then to hydrophobic.The AOB-Y8 surface at 50%CH₃CN content showed the maximum contact angle?151.2o?.In addition,when the CH₃CN content was 50%and the sample concentration was reduced from 5 mg mL^-1 to 1 mg mL^-1,the adhesion force increased from 13?N to 85?N.We analyzed the change in adhesion through the Cassie and Wenzel models.By calculating the Hansen solubility parameter components??_d,?_p,and?_h?of the mixed solvent,it is shown that the self-assembly morphology and the change in wettability are mainly affected by the polarity parameter?_p of the mixed solvent.At the same time,UV-vis absorption spectroscopy studies showed that there exists?-?interaction in the self-assembly structure of AOB-Y8.XRD studies demonstrated that the superhydrophobic surface of AOB-Y8 favors the lamellar structure.In addition,the self-assembly morphology and wettability of AOB-Y8 are also affected by the crystallization temperature and light illumination.Meanwhile,the AOB-Y8 self-assembled surfaces showed an excellent chemical resistance to acid and alkali,which is suitable for applications in many environmental conditions.The tunable adhesive superhydrophobic AOB-Y8 surfaces demonstrated good features to be used in selective transportation of droplets,self-cleaning and droplet-based microreactor.In addition,the research results obtained in this paper provide an important basis for the later application of this kind of light-responsive material in other fields.