CONSTRUCTION OF LUMINESCENT TERBIUMINORGANIC/ORGANIC MOLECULAR-BASED HYBRIDSFROM MODIFIED FUNCTIONAL BRIDGE LIGANDBing Yan*, Li-Min Zhao.Department of Chemistry, Tongji University, China (2004).Source: Science DirectNURUL ASHIKIN BT. ABD RAHMAND20091034935
4-Tert-butylbenzoic acid (TBBA) was modified to achieve a functionalmolecular bridge (TBBA-APMS) with double reactivity by the amidationreaction by a cross-linking molecule (3-aminopropyl)trimethoxysilane(abbreviated as APMS). The modified functional ligand further behavesas a bridge which can both coordinate to terbium ion through amide’oxygen atom and occur an in situ sol-gel process with matrix precursor(tetraethoxysilane, TEOS), resulting a novel molecular hybrid material(named as Tb-TBBA-APMS) with double chemical bond (Tb–Ocoordination bond and Si–O covalent bond). Ultraviolet absorption,phosphorescence, and fluorescence spectra were applied tocharacterize the photophysical properties of the obtained hybridmaterial. The strong luminescence of Tb3+ substantiates optimumenergy couple and effective intramolecular energy transfer between thetriplet state energy of modified ligand bridge and emissive energy levelof Tb3+ .
Inorganic-organic hybrid materials can devide into:• Preparation & characterization of molecular hybrid material (Tb-TBBA-APMS)hydrolysis polycondensation So-gel technologyChemical bonded with strongcovalent bond linking theorganic and inorganic.Physically mixed with weakinteractions between theorganic and inorganic phasesSo-gel technology: method for the preparation of inorganic-organichybrid materials
TBA-APMSethanol+ TEOSH2OTb(NO3)3.6H2Odilutedhydrochloric2 ml DMF +hexamethylenetetramine60 CStrir untilsamplesolidifiedCharacterize the photophysicalproperties of obtained hybrid materialFilter the productformed
Hydrolysis and polycondensation processes between TBBA-APMS and TEOS
IR SpectraBand located Characteristicabsorption1688 cm-1 Acyl chloride1640 cm-1 Amie group(-CO-NH-)Formation wavelengthAmide group stretching vibration( vNH , 3376 cm-1) & bendingvibration (ᵹNH, 1554cm-1)(Si-C) bond Stretching vibration : 1198cm-1Siloxane bonds absorption band at 1018 cm-1(vSi–O–Si )
CUltraviolet absorption spectraii :258 nmi: 248 nm• Electron distribution of themodified TBBA-APMS has hardlychanged compared to free TBBAligand for the introduction ofAPMS group.A: TBBAB: TBBA-APMSC: Tb-TBBA-APMS hybrids• 10 nm (258-248 nm) is observedon addition of Tb3+ to TBBA-APMS, proving the formation of acomplex between Tb3+ and TBBA -APMS.
Phosphorescence spectra at 77KTBBATBBA-APMS• Different phosphorescencebands correspond to differentligand moleculesii :424 nmi :406 nm• Modification of amino groupbetween A (406nm) and B(424nm)
Excitation spectrum of Tb-TBBA-APMS hybrid materialABCDA: 247.5 nmB: 256.0 nmC: 352.5 nmD: 374.5 nmBoth these excitationspectra bands are theeffective absorption for theluminescence of Tb3+
Emission spectrum of Tb-TBBA-APMS hybrid materials• Strong green luminescencewas observed .• Effective energy transferbetween the aromatic ligandTBBA-APMS and the chelatedTb3+ ions.488.5543.5583.0621.5
• Hydrolysis and polycondensation reactions betweentriethoxysilyl of TBBA-APMS and TEOS lead to theformation of Si-O-Si network structures for the samealkoxy groups.• A novel luminescent molecular-based hybrid material withdouble chemical bond was firstly constructed using TBBA-APMS coordinated to Tb3+ .• This technology can be expected to the assembly otherluminescent molecular-based hybrid material.
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