| Biological water(BW),which refers to the water molecules in the solvation layer adjacent to biomolecules,is essential for the construction of protein conformation and adjustment of physiological functions.Therefore,understanding the B W in a molecular level is the key to reveal the physiological functions of biological macromolecules.However,the ultrafast reorientation of hydrogen-bonding network(HBN)and the complexity of biomolecular structure increase the research difficulty of BW.FpR based metal-carbonyl vesicles(MCsomes)have bi-layered vesicular membrane.Taking advantage of the simple structure and the presence of hydration cavity,the FpR MCsomes are expected to be an ideal model to simulate the hydrated biological assemblies.However,whether the existence of water molecules is in the FpR membrane and how such water molecules affect the assembling behavior at both the molecular and supramolecular level are yet to be understood,which limits the exploration of small molecular hydrated assembly.To overcome these challenges,we used Raman spectroscopy and solute correlated(SC)spectral separation treatment to investigate the number and structure of water molecules in the membrane of FpR MCsomes,and thus proving that the FpR MCsomes are a new type of hydrated assemblies.The combination of the hydration structure and assembling behavior was further investigated by regulating the degree of order of HBN.By adjusting the molecular structure and composition of FpR building block(BB),surface charge and assembling solvent,we not only tuned the swelling behavior,the isomerization rate of functional groups and the emission behavior at supramolecular level,but also revealed the integration and restriction of hydration environment at molecular level.These results provide a novel model and method for understanding the role of BW in biological macromolecules.The main contents are described as follows:1.Hydration structure and assembling behavior of FpR MCsomesFpR MCsomes was measured by Raman spectroscopy with SC spectral separation treatment.The OH vibration of interstitial water was then obtained.The SC spectrum reveals that a large amount of water molecules was trapped in the membrane.These interstitial water forms an ordered HBN and the relatively degree of order depends on the structure of BB.The degree of order for those BB containing aromatic groups(FpC6Pyrene and FpC3Bithiophene)are higher and that for the BB with alkyl chain(FpC6)are lower.The Raman spectrum,fluorescence spectrum and the variation of hydration diameter of the FpC6Pyrene MCsomes revealed the function of HBN at molecular and supramolecular levels:the HBN separated the BB so that no direct molecular contact in this system,but it can act as a medium to integrate the MCsomes.These results show that the FpR MCsomes are a new type of hydrated assemblies.By studying the swelling behavior of FpC6 MCsomes,it was found that the reason for the swelling is the decomposition of HBN with low degree of order.Furthermore,FpC6Pyrene and FpC6 were mixed with different molar ratio to form co-assemblies with varied HBN and thus achieved the adjustment of hydration environment and swelling behavior.2.Effect of the adjusted surface charge on the hydration environment of FpR MCsomesBased on the hydration environment of FpR MCsomes,the surfactant/FpR composite MCsomes were constructed by intercalating alkyl surfactant into the membrane through hydrophobic effect.It was shown that the formation of hostguest structure depends on the length of the alkyl chains of the guest molecules but is not affected by the ionic head,which further proved that this process is driven by hydrophobic effect rather than electrostatic interaction.The hostguest structure of the C16N+/FpR and C16SO32-/FpR composite MCsomes can be described as:the end of guest molecules inserting into the membrane while the ion head exposing to water.Based on this structure,the inner membrane polarity,molecular isomerization rate and the swelling behavior were investigated to reveal the influence of the surfactants on the hydration environment of FpR MCsomes:the cationic head of C16N+barely change the hydration environment but can protect the MCsomes in acid or salty solutions,while the intercalated C16 chains promote the degree of order of HBN;the anion head of C16SO32affect the hydration environment in a wide range,which decreases the degree of order of HBN within the membrane while formats a pyknotic hydration layer over the MCsomes.Moreover,the intercalation of C18N+with longer alkyl chain can repel most of water,which converts the hydration structure to a hydrophobic collapse structure.3.Water-mediated through space conjugation of FpC3Bithiophene MCsomes for photoluminescenceIn this thesis,the photoluminescent mechanism of the FpC3Bithiophene MCsomes was investigated based on its hydration structure and fluorescent characteristics.By modulating the solvent composition and assembling conditions,the hydrated environment,molecular conformation and fluorescence were adjusted and the mechanism of water-mediated throughspace-conjugated photoluminescence was then proposed:when the conformation of bithiophene is torsional,the formed conjugated structure can emit visible photoluminescence;while the planar chromophore extends the conjugation level and dissipates the energy via non-radiation that quenches the photoluminescence;as the end groups of FpR MCsomes were restricted by the HBN,the intramolecular rotation and conformational conversion of bithiophene groups can be achieved by adjusting the degree of order of HBN.Based on this mechanism,the fluorescence intensity of the FpC3Bithiophene MCsomes was finely tuned and a new type of functional hydration assemblies with stimuliresponsive photoluminescence was created.To sum up,by investigating the hydration structure,behavior and function of FpR MCsomes,this thesis lays the foundation for the research of new hydrated assemblies and extends the theory of water-mediated function.It also provides a novel model for simulating the role of BW in biological macromolecules. |
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