Synthesis,Characterization And Third-Order Nonlinearity And Optical Limiting Properties Of Four High-Core Polyacid-Porphyrin/phthalocyanine Compounds

Two types of porphyrin/phthalocyanine and polyoxometallate(POM)composites with different combinations of forces were synthesized,and their third-order nonlinear optical(NLO)response and optical limiting(OL)were analyzed by Z-scan technique.The performance was studied,and the mechanism of nonlinear optical response of porphyrin/phthalocyanine-polyoxometallate system and the mechanism of optical limiting were analyzed and explained.(1)In this chapter,we have selected two kinds of giant-wheeled polyacids Na15(MO?126Mo?28O462H14(H2O)70)0.5(Mo?124Mo?28O457H14(H2O)68)0.5·ca.173 H2O and Na16[(MoO3)176(H2O)63(CH3OH)17H16]·ca.76H2O containing different numbers of molybdenum atoms,a large number of proton donors inside the giant wheel(?3-O…H)and 5,10,15,20-zinc tetrahydroxyphenyl porphyrin(C44H28N4O4Zn,abbreviated the proton acceptor hydroxyl groups of ZnTHPP are linked by hydrogen bonding with two porphyrin-polyacid compounds Na15[(Mo?126Mo?28O462H14(H2O)70)0.5(Mo?124Mo?28O457H14(H2O)68)0.5][C44H28N4O4Zn]3·ca.78H2O(Compound 1)and Na16[(MoO3)176(H2O)63(CH3OH)17H16][C44H28N4O4Zn]3·ca.72H2O(Compound 2).The two compounds were characterized by IR,UV,elemental analysis,thermogravimetry and inductively coupled plasma emission spectroscopy.The Z-Scan technique(532 nm,6 ns)was used to study the third-order NLO response and OL properties.The second-order supramolecular polarizabilities(?)of compound 1 and 2 reached 62.81×10-28(esu)and 76.04×10-28(esu)respectively,and were much higher than 9.76×10-28(esu)(esu)of ZnTHPP.The limiting threshold sequence is:ZnTHPP>Compound 1(0.12 J/cm2)>Compound 2(0.10 J/cm2),and the nonlinear attenuation factor(NAF)order is:Compound 2(17.75)>Compound 1(14.4)>ZnTHPP(2.67).The above results indicate that the synergistic mechanism of polyacids and porphyrins can significantly enhance their anti-saturation absorption response,thereby improving the optical limiting performance.The LUMO energy level difference between porphyrin and polyacid is positively correlated with the second-order supramolecular polarizability of the compound,so the nonlinear response and optical limiting performance of the compound can be improved by introducing a polyacid with a lower LUMO energy level.(2)In this chapter,we successfully synthesized two kinds of Keplerate-based polyacids(NH4)72[(H20)81(?)(Mo?)Mo?5O21(H2O)6}12{Mo?2O4(SO4)}30]·200H2O and different conjugated macrocycles(porphyrin(C44H32N4O12Cl2,denoted as[H2THPP](ClO4)2)/phthalocyanine([(C5H5N)4(C6H3)4N8CuC8]Cl4,denoted as AB-Pc)))(NH4)62[C44H32N4O4]5[(H2O)81(?){(Mo?)Mo?5O21(H2O)6}12{Mo?2O4(SO4)}30]·181H2O(compound 1);(NH4)52[(C5H5N)4(C6H3)4N8CuC8)]5[(H2O)81(?){(Mo?)Mo?5O21(H2O)6}12{MO?2O4(SO4)}30]·186H2O(Compound 2).It is characterized by infrared,thermogravimetric analysis,spectral titration,cyclic voltammetry and other testing methods.The third-order NLO response and OL properties were studied by Z-Scan technique(532 nm,6 ns).The order of y values was:compound 1(10.078×10-28 esu)>compound 2(8.130×10-28 esu)>[H2THPP](ClO4)2(4.387×10-28 esu)>AB-Pc(3.135×10-28 esu),the order of NAF value is Compound 1(8.875)>Compound 2(6.636)>[H2THPP](ClO4)2(2.26)>AB-Pc(1.8),the limiting threshold order is:compound 1(0.34 J/cm2)<compound 2(0.49 J/cm2)<[H2THPP](ClO4)2(8 J/cm2)<AB-Pc.The ? value and optical limiting properties of the compounds are positively correlated with the LUMO energy level difference of porphyrin/phthalocyanine and polyacid.The reason is mainly the electron transfer from organic component to Donor-and-Acceptor.