The Birth of Fluorescence from Thermally Polymerized Glycine

Cossu, Franca; Poddighe, Matteo; Stagi, Luigi; Anedda, Roberto; Innocenzi, Plinio

doi:10.1002/macp.202200052

Cited by 8 publications

(5 citation statements)

References 24 publications

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“…0.128 g of l -lysine were solubilized in 10 mL of distilled H 2 O (0.87 M). The solutions were placed into a Teflon-lined stainless steel autoclave 7 with a capacity of 50 mL and then heated at 130 or 200 °C for 15 h. After the hydrothermal treatment (HT), the obtained products were cooled down to 20 °C and then used for the characterizations. The samples hydrothermally treated at 130 and 200 °C are indicated in the text as HT-130 °C and HT-200 °C.…”

Section: Methodsmentioning

confidence: 99%

Modulating the poly-l-lysine structure through the control of the protonation–deprotonation state of l-lysine

Stagi

Sini

Carboni

et al. 2022

Sci Rep

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Designing the architecture of l-lysine-based polymeric structures is a highly challenging task that requires careful control of the amino acid reactive groups. Conventional processes to obtain branched polylysine need several steps and the addition of specific catalysts. In the present work, to gain a better understanding and control of the formation of l-lysine-based polymers, we have investigated the correlation between the protonation state of l-lysine and the corresponding hydrothermally grown structures. The samples have been characterized by combining optical spectroscopies, such as UV–Vis, fluorescence, and synchrotron radiation circular dichroism with structural analysis by Nuclear Magnetic Resonance, Fourier Transform Infrared spectroscopy, and dynamic light scattering. We have observed that aqueous precursor solutions with alkaline pHs promote the formation of branched structures. In contrast, high pHs favour the reactivity of the ε-amino groups leading to linear structures, as shown by circular dichroism analyses. On the other hand, acidic conditions trigger the branching of the amino acid. Interestingly, the polymeric forms of l-lysine emit in the blue because the increasing number of intermolecular hydrogen bonds promote the intermolecular charge transfer responsible for the emission. Understanding the correlation between the l-lysine charged states and the polymeric structures that could form controlling the protonation–deprotonation states of the amino acid opens the route to a refined design of polypeptide systems based on l-lysine.

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Section: Methodsmentioning

confidence: 99%

Modulating the poly-l-lysine structure through the control of the protonation–deprotonation state of l-lysine

Stagi

Sini

Carboni

et al. 2022

Sci Rep

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“…Our research group has experimentally demonstrated that polymers with strong emission in the blue region can be obtained from nonaromatic amino acids such as l -lysine and glycine …”

Section: Introductionmentioning

confidence: 99%

“…7,8 Our research group has experimentally demonstrated that polymers with strong emission in the blue region can be obtained from nonaromatic amino acids such as L-lysine 2 and glycine. 9 L-lysine, in particular, forms branched and hyperbranched structures via thermal polymerization. These polymers are chromophores and exhibit well-defined lifetime, quantum yield, and correlated absorption−emission spectra.…”

Section: ■ Introductionmentioning

confidence: 99%

Design of Dual-Emitting Nonaromatic Fluorescent Polymers through Thermal Processing of l-Glutamic Acid and l-Lysine

Cadeddu,

Carboni,

Stagi

et al. 2024

Macromolecules

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Fluorescence emission of proteins containing aromatic groups and conjugated bonds is generally associated with light absorption in the ultraviolet range, around 185−320 nm. Photoluminescence in nonaromatic biopolymers, however, has also been observed in amyloid-like structures and polymers derived from L-lysine and glycine. Here, we show, for the first time, that branched polymers obtained through thermal copolymerization of two nonaromatic amino acids, L-lysine and L-glutamic acid, exhibit twocolor centers with relative absorptions in the visible range. Thermal homopolymerization of L-lysine or L-glutamic acid gives rise to the formation of branched polyglutamic acid and polylysine with a single fluorescence emission peaking at around 450 nm. The coreaction of the two amino acids produces instead a branched peptide-like polymer with a new emission centered at around 380 nm. The structures of the copolymers were studied by differential scanning calorimetry, in situ temperature-resolved FTIR, NMR, and TEM spectroscopy techniques. The optical properties were investigated by UV−vis and fluorescence spectroscopy. The double emission can be correlated with two different intramolecular charge transfer processes between the polymer backbone and the oppositely charged moieties of the two precursor side chains, Lys and Glu, which are at the origin of near-UV fluorescence.

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“…This interest is partly due to glycine's simple structure, high solubility in water, and its role as a building block for proteins, making it an ideal candidate for synthesizing complex materials through thermal treatment or polymerization processes. Its simplicity (composed merely of a backbone connected to a single hydrogen atom) facilitates easier manipulation and predictable outcomes during synthesis procedures, allowing for the formation of linear peptides through thermal polymerization, even under conditions that are not typically favorable for such reactions [22]. Moreover, during heat treatment, glycine displays distinctive characteristics, such as being able to participate in decarbonylation and cyclodehydration reactions, ultimately contributing to the generation of heterocycles relevant to CN x materials.…”

Section: Introductionmentioning

confidence: 99%

On a Composite Obtained by Thermolysis of Cu-Doped Glycine

Chamorro-Posada,

Dante,

Martín-Gil

et al. 2024

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Metal-doped carbonaceous materials have garnered significant attention in recent years due to their versatile applications in various fields, including catalysis, energy storage, environmental remediation, electronics, and sensors, as well as reinforcement. This study investigates the synthesis and characterization of a composite material featuring a carbonaceous matrix doped with copper, focusing on the thermolysis of glycine as a precursor. The synthesis methodology involved utilizing glycine and copper acetate monohydrate in varying ratios, with the mixture subjected to heating in ceramic crucibles at temperatures ranging from 450 to 550 °C, with pyrolysis yields over the 5 to 39% interval. The pristine and Cu-doped samples obtained at 500 °C underwent characterization using a diverse array of techniques, including scanning and transmission electron microscopies, multi-elemental analysis by energy dispersive X-ray spectroscopy, CHNS elemental analysis, X-ray photoelectron spectroscopy, X-ray powder diffraction, infrared and Raman spectroscopies, ultraviolet-visible spectroscopy, and terahertz time-domain spectroscopy, along with conductivity measurements. Under optimized conditions, copper (at 6.5%) was present primarily in the free metallic form, accompanied by traces of tenorite (CuO) and cuprite (Cu2O). The carbonaceous matrix exhibited a 6:1 ratio of graphitic carbon to a carbon-nitrogen compound with the formula C2H2N2O2, such as isomers of diazetidinedione, according to multi-elemental analysis results. Conductivity measurements disclosed a significant increase in conductivity compared to the product of glycine thermolysis, showcasing the enhanced electrical properties of the new composite. Additionally, terahertz measurements showed the potential of the material as a broadband absorber for the fabrication of terahertz devices and provided compelling evidence of a significant improvement in radiation absorption upon copper doping. In conclusion, this research sheds light on the promising properties of copper-doped carbonaceous composites obtained by glycine pyrolysis, offering insights into their potential applications in emerging technological domains.

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The Birth of Fluorescence from Thermally Polymerized Glycine

Cited by 8 publications

References 24 publications

Modulating the poly-l-lysine structure through the control of the protonation–deprotonation state of l-lysine

Modulating the poly-l-lysine structure through the control of the protonation–deprotonation state of l-lysine

Design of Dual-Emitting Nonaromatic Fluorescent Polymers through Thermal Processing of l-Glutamic Acid and l-Lysine

On a Composite Obtained by Thermolysis of Cu-Doped Glycine

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