## 3 Results and Discussion  
### Characterization of Zn-MOF-8@AgQDs Composite  
The chemical structure of the samples was investigated by FTIR spectroscopy. Figure 1a,b displays FTIR spectra of the prepared zinc metal complex and their composite in the range of 400-4000 cm\({}^{-1}\). In Figure 1, the zinc-metal complex showed the absorption frequency at 3400 cm\({}^{-1}\) which confirms the presence of hydroxyl group in the complex. Peaks appearing at 3118 cm\({}^{-1}\) and 1612 cm\({}^{-1}\) were assigned due to C-H stretching present in aromatic ring of the linker and C=O stretching lower than those of napthalenedicarboxylic acid, respectively which confirmed the coordination of Zn metal. The absorption band at 1557 cm\({}^{-1}\) and 1492 cm\({}^{-1}\) confirmed the aromatic C=C bending vibrations whereas the absorption at 927 cm\({}^{-1}\), 792 cm\({}^{-1}\) and 648 cm\({}^{-1}\) was due to presence of small amount of dimethylformamide as residual solvent. The absorption peaks at 482 cm\({}^{-1}\) correspond to Zn-O stretching which confirmed the structure of the metal coordination bond in the complex. There was no absorption peak at 1700 cm\({}^{-1}\) which implies that carboxyl group of 2,6-naphthalenedicarboxylic acid was completely removed during the reaction. Figure 1b depicts the FTIR spectrum of ZnMOF-8@AgQDscomposite indicating partial changes in the peak value due to encapsulation of Ag QDs into the pores of MOFs. The extra peak appearing at about 530 cm\({}^{-1}\) corresponds to stretching of the Ag-O bond and the peak at 2373 cm\({}^{-1}\) was due to air in the atmosphere. The crystallinity, structure and phase composition of Zn-MOF-8 and its composite were analyzed by XRD, which displayed patterns for Zn-MOF-8, similar to that of the single crystal structure of Zn-MOF-8 as prepared by solvothermal method. The number of well-defined diffraction peaks at various positions in the complex was confirmed by powder-XRD and the crystalline nature of the metal complexes was observed (Figure 1c,d). In Figure 1c, the sharp and intense peak in P-XRD confirmed the monoclinic crystal system with space group P2\({}_{1}\)/c. For Zn-MOF-8@Ag composite (Figure 1d), the P-XRD pattern was comparable to that of Zn-MOF-8 crystal except for strong peaks observed at 38\({}^{\circ}\) and 44\({}^{\circ}\) and 60\({}^{\circ}\) which corresponds to the (111), (200) and (108) planes of silver QDs particles [39; 40; 41]. To investigate the thermal stability of the nanostructure metal complex and its composite, thermal gravimetric analysis (TGA) was performed in the temperature range from 25-1000 \({}^{\circ}\)C under nitrogen atmosphere (Figure 2). The TGA curve of Zn-MOF-8 revealed that weight loss initiated with the removal of water and dimethylformamide molecules around 100-200 \({}^{\circ}\)C whereas the second prominent mass loss was seen around 500-530 \({}^{\circ}\)C which is due to structural decomposition of organic linkers (Figure 2a). However, in the case of the composite, the weight loss started around 100-200 \({}^{\circ}\)C and the second weight loss occurred round 450 \({}^{\circ}\)C due to large amount of metallic species in the composite (Figure 2b). The third weight loss occurred around 650 \({}^{\circ}\)C which corresponded to the degradation of metal framework. The results clearly showed that the weight loss of Zn-MOF-8@AgQDs was detected at relatively higher temperature, which indicated high thermal stability of the MOF after incorporation of Ag nanoparticles. Figure 1: FTIR spectra of (**a**) Zn–MOF-8, (**b**) Zn–MOF-8@AgQDs (**c**) Powder- XRD of Zn–MOF-8 and (**d**) Zn–MOF-8@AgQDs. The morphology and size of the metal complex and its composite were examined by TEM. TEM images of the Zn-MOF-8 nanoparticles and its QDs composite are shown in Figure 3. The Zn-MOF-8 showed cube-shaped morphologies with size in the range of \(\sim\)186 nm (Figure 3b). Moreover, Zn-MOF-8@Ag composite confirmed that Ag particles were adhering to the Zn-MOF-8 surface.