The green tea-assisted synthesis of metal complexes (MCs) in water-based solutions, which enhances environmental impact and reduces costs, is crucial for bringing laboratory MC research into commercial applications. A composite of polar polyvinyl alcohol (PVA) and manganese MCs was produced utilizing the casting technique. The interaction parameters between MnMC and PVA have been studied using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and UV-visible spectroscopies. According to XRD spectra, the addition of MCs decreased the crystallinity of the PVA semi-crystalline polymer. FTIR was used to study MnMC's functional groups and chemical interactions with PVA's hydroxyl (OH) functional groups. The FTIR results indicate that the peaks at 1416 and 1566 cm⁻1 correspond to the symmetric and asymmetric stretching of the carboxylate group (COO-) in Mn(CH3COO)2. However, these peaks are absent in MnMC, suggesting that GT polyphenols become ligands in MnMC. UV-vis study showed a decrease in the optical energy band gap <InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="42247_2025_1102_Article_IEq1.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="21" /> </InlineMediaObject> <EquationSource Format="TEX">\({E}_{g}\)</EquationSource> </InlineEquation> from 6.05 to 1.52 eV, indicating increased structural disorder at the PVA-MnMC interface. Different models have been used to calculate <InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="42247_2025_1102_Article_IEq1.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="21" /> </InlineMediaObject> <EquationSource Format="TEX">\({E}_{g}\)</EquationSource> </InlineEquation> such as; <InlineEquation ID="IEq3"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="42247_2025_1102_Article_IEq3.gif" Format="GIF" Height="23" Rendition="HTML" Resolution="72" Type="Linedraw" Width="201" /> </InlineMediaObject> <EquationSource Format="TEX">\(\alpha, {\varepsilon }_{i},\frac{dT}{d\lambda },\frac{dR}{d\lambda }, tan\delta, {\sigma }_{opt}, \text{ln}(A)\)</EquationSource> </InlineEquation> vs hv, and the Tauc model is used to establish the type of electron transitions. The Wemple and DiDomenico model was used to find <InlineEquation ID="IEq4"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="42247_2025_1102_Article_IEq4.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="22" /> </InlineMediaObject> <EquationSource Format="TEX">\({E}_{d}\)</EquationSource> </InlineEquation>,<InlineEquation ID="IEq5"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="42247_2025_1102_Article_IEq5.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="21" /> </InlineMediaObject> <EquationSource Format="TEX">\({E}_{o}\)</EquationSource> </InlineEquation> and <InlineEquation ID="IEq6"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="42247_2025_1102_Article_IEq6.gif" Format="GIF" Height="12" Rendition="HTML" Resolution="72" Type="Linedraw" Width="19" /> </InlineMediaObject> <EquationSource Format="TEX">\({n}_{o}\)</EquationSource> </InlineEquation> and also used to calculate the interband transition strength moments <InlineEquation ID="IEq7"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="42247_2025_1102_Article_IEq7.gif" Format="GIF" Height="17" Rendition="HTML" Resolution="72" Type="Linedraw" Width="33" /> </InlineMediaObject> <EquationSource Format="TEX">\({M}_{-1}\)</EquationSource> </InlineEquation> and <InlineEquation ID="IEq8"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="42247_2025_1102_Article_IEq8.gif" Format="GIF" Height="17" Rendition="HTML" Resolution="72" Type="Linedraw" Width="33" /> </InlineMediaObject> <EquationSource Format="TEX">\({M}_{-3}\)</EquationSource> </InlineEquation>. The composite samples' Urbach energy increased to 0.56 eV, demonstrating a rise in defect density due to the integration of MnMC. Compared to pure PVA, PVA/MnMC composites exhibit improved index of refraction (n), optical dielectric constants (εr and εi), optical conductivity, 3rd-order nonlinear optical susceptibility χ(3), nonlinear index of refraction n(2), linear optical susceptibility χ(1), surface resistance Rs, and merit figure. PVA/MnMC will improve the linear and nonlinear optical characteristics of photocells, optoelectronics, and photonic device applications. This study examined the impact of green tea-assisted synthesis of metal complexes on PVA, surpassing the effects of conventional doping methods, including ceramic fillers, polymer electrolytes, and nanoparticle systems.

Green synthesized inorganic Mn-metal complex as a novel approach to modify the optical band gap of PVA polymer

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发表日期：

2025年5月9日

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Dana S. Muhammad,
Dara M. Aziz,
Shujahadeen B. Aziz

摘要

The green tea-assisted synthesis of metal complexes (MCs) in water-based solutions, which enhances environmental impact and reduces costs, is crucial for bringing laboratory MC research into commercial applications. A composite of polar polyvinyl alcohol (PVA) and manganese MCs was produced utilizing the casting technique. The interaction parameters between MnMC and PVA have been studied using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and UV-visible spectroscopies. According to XRD spectra, the addition of MCs decreased the crystallinity of the PVA semi-crystalline polymer. FTIR was used to study MnMC's functional groups and chemical interactions with PVA's hydroxyl (OH) functional groups. The FTIR results indicate that the peaks at 1416 and 1566 cm⁻¹ correspond to the symmetric and asymmetric stretching of the carboxylate group (COO^-) in Mn(CH₃COO)₂. However, these peaks are absent in MnMC, suggesting that GT polyphenols become ligands in MnMC. UV-vis study showed a decrease in the optical energy band gap \({E}_{g}\) from 6.05 to 1.52 eV, indicating increased structural disorder at the PVA-MnMC interface. Different models have been used to calculate \({E}_{g}\) such as; \(\alpha, {\varepsilon }_{i},\frac{dT}{d\lambda },\frac{dR}{d\lambda }, tan\delta, {\sigma }_{opt}, \text{ln}(A)\) vs hv, and the Tauc model is used to establish the type of electron transitions. The Wemple and DiDomenico model was used to find \({E}_{d}\) , \({E}_{o}\) and \({n}_{o}\) and also used to calculate the interband transition strength moments \({M}_{-1}\) and \({M}_{-3}\) . The composite samples' Urbach energy increased to 0.56 eV, demonstrating a rise in defect density due to the integration of MnMC. Compared to pure PVA, PVA/MnMC composites exhibit improved index of refraction (n), optical dielectric constants (ε_r and ε_i), optical conductivity, 3^rd-order nonlinear optical susceptibility χ⁽³⁾, nonlinear index of refraction n⁽²⁾, linear optical susceptibility χ⁽¹⁾, surface resistance R_s, and merit figure. PVA/MnMC will improve the linear and nonlinear optical characteristics of photocells, optoelectronics, and photonic device applications. This study examined the impact of green tea-assisted synthesis of metal complexes on PVA, surpassing the effects of conventional doping methods, including ceramic fillers, polymer electrolytes, and nanoparticle systems.