CONSTRUCTION OF LUMINESCENT TERBIUM INORGANIC/ORGANIC MOLECULAR-BASED

HYBRIDS FROM MODIFIED FUNCTIONAL BRIDGE LIGANDBing Yan*, Li-Min Zhao.

Department of Chemistry, Tongji University, China (2004).Source: Science Direct

NURUL ASHIKIN BT. ABD RAHMAND20091034935

ABSTRACT

4-Tert-butylbenzoic acid (TBBA) was modified to achieve a functional molecular bridge (TBBA-APMS) with double reactivity by the amidation reaction by a cross-linking molecule (3-aminopropyl)trimethoxysilane (abbreviated as APMS). The modified functional ligand further behaves as 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–O coordination bond and Si–O covalent bond). Ultraviolet absorption, phosphorescence, and fluorescence spectra were applied to characterize the photophysical properties of the obtained hybrid material. The strong luminescence of Tb3+ substantiates optimum energy couple and effective intramolecular energy transfer between the triplet state energy of modified ligand bridge and emissive energy level of Tb3+ .

Inorganic-organic hybrid materials can devide into:

• Preparation & characterization of molecular hybrid material (Tb-TBBA-APMS)

OBJECTIVE

INTRODUCTION

hydrolysis

polycondensati

on

So-gel technolo

gy

Chemical bonded with strong covalent bond linking the organic and inorganic.

Physically mixed with weak interactions between the organic and inorganic phases

So-gel technology: method for the preparation of inorganic-organic hybrid materials

EXPERIMENTAL

TBA-APMS

ethanol + TEOS

H2O

Tb(NO3)3.6H2O

diluted hydrochloric

2 ml DMF + hexamethylenetetramine

60 C

Strir until sample solidified

Characterize the photophysical properties of obtained hybrid material

Filter the product formed

FTIR Spectrophotometer• Measure Infrared

spectroscopy

Agilent Spectrophotometer• Measure ultraviolet

absorption.

Perkin-Elmer Spectrophotometer• Measure fluorescence,

excitation and emission spectra

AP

Ether,Pyridine, Ar

TBBA

TBBA-APMS

Preparation o f TBBA-APMS

Predicted Structure Of Hybrid Materials

Hydrolysis and polycondensation processes between TBBA-APMS and TEOS

RESULT & DISCUSSION

IR Spectra

Band located Characteristic absorption

1688 cm-1 Acyl chloride

1640 cm-1 Amie group (-CO-NH-)

Formation wavelengthAmide group stretching vibration

( vNH , 3376 cm-1) & bending vibration (ᵹNH, 1554 cm-1)

(Si-C) bond Stretching vibration : 1198 cm-1

Siloxane bonds absorption band at 1018 cm-1

(vSi–O–Si )

C

Ultraviolet absorption spectra

ii :258 nm

i: 248 nm

• Electron distribution of the modified TBBA-APMS has hardly changed compared to free TBBA ligand for the introduction of APMS group.

A: TBBAB: TBBA-APMSC: Tb-TBBA-APMS hybrids

• 10 nm (258-248 nm) is observed on addition of Tb3+ to TBBA-A PMS, proving the formation of a complex between Tb3+ and TBBA -APMS.

Phosphorescence spectra at 77K

TBBA

TBBA-APMS

• Different phosphorescence bands correspond to different ligand molecules

ii :424 nm

i :406 nm

• Modification of amino group between A (406nm) and B (424nm)

Excitation spectrum of Tb-TBBA-APMS hybrid material

A B CD

A: 247.5 nmB: 256.0 nmC: 352.5 nmD: 374.5 nm

Both these excitation spectra bands are the effective absorption for the luminescence of Tb3+

Emission spectrum of Tb-TBBA-APMS hybrid materials

• Strong green luminescence was observed . • Effective energy transfer

between the aromatic ligand TBBA-APMS and the chelated Tb3+ ions.

488.5

543.5

583.0

621.5

• Hydrolysis and polycondensation reactions between triethoxysilyl of TBBA-APMS and TEOS lead to the formation of Si-O-Si network structures for the same alkoxy groups.

• A novel luminescent molecular-based hybrid material with double chemical bond was firstly constructed using TBBA-APMS coordinated to Tb3+ .

• This technology can be expected to the assembly other luminescent molecular-based hybrid material.

CONCLUSIONS

REFFERENCES

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• C. Molina, K. Dahmouche, C.V. Santilli, Chem. Mater. 13 (2001) 2818.

• B. Yan, Q.Y. Xie, Inorg. Chem. Commun. 6 (2003) 1448.

• B. Yan, Q.Y. Xie, J. Mol. Struct. 688 (2004) 73.