Aldehyde Functional Groups Research Articles

Reactivity Control of Polymer Functional Groups by Altering the Structure of Thermoresponsive Triblock Copolymers.

A thermoresponsive ABA triblock copolymer bearing an aldehyde group on the thermoresponsive A segments was synthesized. The polymer formed a micellar assembly due to the hydrophobic interactions of the thermoresponsive segment above the lower critical solution temperature (LCST). In contrast, the ABA polymer assembly decomposed upon lowering the temperature below the LCST. Using this structural change, the reactivity of the aldehyde group toward primary amines of albumin and poly(allylamine) was investigated. When the ABA polymer assembly and reactant were mixed above the LCST, Schiff base formation was suppressed because of the aldehyde group being protected by the hydrophobic thermoresponsive core. In contrast, Schiff base formation between the ABA triblock copolymer and the primary amine moiety on the molecules was confirmed below the LCST. The reactivity of the aldehyde functional group can therefore be controlled by altering the structure of the thermoresponsive ABA polymer.

The butoxylation of dodecylamine: Reaction mechanism and kinetics

The reaction mechanism and kinetics of the butoxylation of dodecylamine were investigated experimentally using a semi-batch, fully liquid process at temperatures ranging from 120 °C to 150 °C and varying stoichiometric ratios of the reactants. In addition, the catalytic effect of adding 1–3%mol of twelve different functional organic species containing hydroxyl, aldehyde, amine, and/or amide functional groups was studied. It was found that only proton donating groups increase the observed reaction rate. In particular hydroxyl groups in combination with an amine group resulted in a strong acceleration of the reaction. Since the reaction intermediates mono-and dibutoxylated amines have this combination, an auto-catalytic reaction mechanism and corresponding rate law are proposed. The kinetic constants were fitted to the experimental data as a function of temperature, following an Arrhenius type of dependency. The results from the model describe the experimental data with 95% accuracy. Moreover, the results show that the butoxylation of dodecylamine, as a model reactant for a short substituted ethylene oxide, with fatty amines, follows the same mechanism and has similar kinetics as epoxide hardening reactions with amines.

Potential of aldehyde bearing N,N-diphenylhydrazone based organic dye in TiO2, ZnO and TiO2/ZnO bilayer semiconductor constituting dye sensitized solar cells

Organic chromophore based on N,N-diphenylhydrazone bearing aldehyde functional group was synthesized and characterized. TiO2 and synthesized ZnO nanorod based semiconducting materials were utilized for preparing working electrodes in dye sensitized solar cells (DSSCs). The prepared ZnO nanorods were analysed by x-ray diffraction, scanning electron microscopy and transmission emission microscopy. DSSCs were fabricated by using TiO2, ZnO and bilayer of TiO2/ZnO coated electrodes. Atomic force microscopic studies were performed for the semiconductor thin films to evaluate the roughness parameters. Maximum solar energy conversion efficiency of 0.062% was acquired from TiO2 based DSSC. ZnO based DSSC shows a lesser efficiency of 0.027%. DSSC fabricated with bilayer electrode shows highest open-circuit potential of 586 mV.

Self-Assembly of Aldehyde Lipids in Water

Lipid based self-assembled structures has been applied for drug delivery systems. It is well known that lipid self-assembled structures depend on the chemical structures of lipids, however the self-assembled structures of oxidized lipids with asymmetrical structures remain unclear. In this study, 1-palmitoyl-2-(9-oxo-nonanoyl)-sn-glycero-3-phosphocholine (9-al) was used to investigate its self-assembly structure. The molecular dynamics (MD) simulation was performed with the system consisting of 128 lipids and 8,960 simple point charge (SPC) water molecules. Initially, all lipids and water molecules were randomly generated in the simulation box, then molecular trajectories were integrated and collected over microsecond times. The results showed that the equilibrium self-assembled structures of 9-al lipid preferred to form a micelle structure. We analyzed the lipid’s angle distribution and the lipid’s chain length to determine the lipid geometry. The results are in agreement with the previous MD simulation (Boonnoy, P.; et al. J. Phys. Chem. Lett. 2015, 6, 4884 – 4888) that showed the deformation of aldehyde lipid bilayer into micelle structure due to their shorter and highly mobile of aldehyde functional group in oxidized chain.

Synthesis, molecular structure, spectroscopic and computational studies on 4-(2-(2-(2-formylphenoxy)ethoxy)ethoxy)phthalonitrile as Functionalized Phthalonitrile

This work presents the synthesis and characterization of a novel compound, 4-(2-(2-(2-formylphenoxy)ethoxy)ethoxy)phthalonitrile as the aldehyde functional group substituted phthalonitrile derivative. The spectroscopic properties of the compound were examined by FT-IR, 1H-NMR, 13C-NMR, UV-vis, MS, elemental analyses. The molecular structure of the compound was also confirmed using X-ray single-crystal data with a theorical comparative approach.

Identification of an Enzyme Catalyzing the Conversion of Sulfoacetaldehyde to 2-Mercaptoethanesulfonic Acid in Methanogens.

Coenzyme M is an essential coenzyme for the biochemical production of methane. This Communication reports on the identification of an enzyme catalyzing the last step in the biosynthesis of coenzyme M in methanogens. Data presented here show that the enzyme, derived from mj1681, catalyzes the conversion of the aldehyde functional group of sulfoacetaldehyde into the thiol group of 2-mercaptoethanesulfonic acid. Thus, a putative coenzyme M synthase (comF) has similarities in sequence with both MJ0100 and MJ0099 proteins previously shown to be involved in the biosynthesis of homocysteine [Allen, K. D., et al. (2015) Biochemistry 54, 3129-3132], and both reactions likely proceed by the same mechanism. In the MJ0100-catalyzed reaction, Rauch has proposed [Rauch, B. L. (2017) Biochemistry 56, 1051-1061] that MJ1526 and its homologues in other methanogens likely supply the sulfane sulfur required for the reaction.

Elucidating Peptidoglycan Structure: An Analytical Toolset.

Peptidoglycan (PG) is a ubiquitous structural polysaccharide of the bacterial cell wall, essential in preserving cell integrity by withstanding turgor pressure. Any change that affects its biosynthesis or degradation will disturb cell viability, therefore PG is one of the main targets of antimicrobial drugs. Considering its major role in cell structure and integrity, the study of PG is of utmost relevance, with prospective ramifications to several disciplines such as microbiology, pharmacology, agriculture, and pathogenesis. Traditionally, high-performance liquid chromatography (HPLC) has been the workhorse of PG analysis. In recent years, technological and bioinformatic developments have upgraded this seminal technique, making analysis more sensitive and efficient than ever before. Here we describe a set of analytical tools for the study of PG structure (from composition to 3D architecture), identify the most recent trends, and discuss future challenges in the field.

Thermo-kinetics and gaseous product analysis of banana peel pyrolysis for its bioenergy potential

This study illustrated the pyrolysis of banana peel (BP) as a potential waste management solution. Samples were characterized through Fourier transform infrared spectrometry (FTIR), elemental analysis, and high heating value (HHV) calculation. After pyrolysis experiments were performed at different heating rates (10, 20, 30, and 40 °C min−1) by using a thermogravimetric analyzer coupled with FTIR (TG-FTIR), the apparent activation energies were computed with Friedman, Kissinger–Akahira–Sunose (KAS), and Flynn–Wall–Ozawa (FWO) methods, and the evolved gaseous products were analyzed simultaneously. During pyrolysis, BP underwent three devolatilization steps accompanied by the evolution of some major gaseous products, including CO2, CH4, H2O, CH3COOH, CC, C6H5OH, HCOOH, and CH3CH2OH. Among them, CC, CH3COOH, and CO2 accounted for approximately 71.56% of the total gaseous products. Gas evolution was more significantly influenced by the pyrolysis temperature than by the heating rate. Pyrolysis–gas chromatography/mass spectrometry (Py-GC/MS) analysis confirmed the presence of some high-energy compounds and valuable chemicals containing aromatic, aldehyde, ketone, and other functional groups. In terms of preliminary energy balance, more than 70% of the total energy output was attributed to the liquid pyrolytic products followed by the solid and gaseous products. The energy recovery ratio of BP pyrolysis was superior to that of other fuel feedstocks. This work provided insights into resolving environmental problems associated with BP management by pyrolyzing BP as a potential source of renewable bioenergy.

Cinnamyl-Imine-Chitosan Hydrogels. Morphology Control

Abstract The study deals with the exploration of the possibilities to control the morphology of cinnamyl-imine-chitosan hydrogels in view of their bio-application. Three series of hydrogels were synthetized from chitosan of three different molecular weights and cinnamaldehyde, varying the molar ratio between the amine groups on chitosan and aldehyde functional groups. The hydrogel morphology has been monitored by scanning electron microscopy. The variation of the hydrogel morphology as a function of chitosan molecular weight, crosslinking degree, and incubation conditions has been monitored. It was concluded that there are multiple possibilities of tuning the morphology of these hydrogels in function of the targeted application.

A novel synthetic approach for the synthesis of pyrano[3,2-c] quinolone-3carbaldehydes by using modified Vilsmeier Haack reaction, as potent antimicrobial agents

This research work is about the synthesis of pyranoquinolone-3carbaldehydes, heterocyclic compounds which were constructed by modifying Vilsmeier-Haack reaction. A leading approach towards green chemistry and successful methodology was devised during this research project for the synthesis of various pyranoquinolone-3-carbaldehydes at low temperature. Some workers reported the synthesis of chromones and chloroquinoline-3carbaldehydes. Interesting aspect of the present work was to successfully utilize two methodologies during a single reaction (one to cyclize a pyran ring and second to insert formyl group) by manipulating the different functional groups attached to the reactants and to construct the desired molecules. In some works, cited during the formylation reaction by using Vilsmeier Haack reagent, halogenated products were reported while in this synthetic study the final products were formylated but nonhalogenated. This methodology is a milestone for the construction of an aldehyde functional group on some parent moieties. The reaction is an example of one pot synthesis. All synthesized compounds were found having several pharmacological characteristics. These derivatives were characterized by FTIR, 1HNMR, EIMS and elemental (C, H and N) analyses; confirming the synthesis of the labelled products. The reactants used in this research project were synthesized by Gould Jacobs reaction prepared during our last research project as cited [26]. The antibacterial activity of ligands and metal complexes was determined by disc diffusion method using Bacillus subtilis, Escherichia coli, and Staphylococcus aureus and got excellent results.

New sensitive strategy for formaldehyde sensing by in situ generation of luminescent silver nanoclusters

A new strategy for the detection of formaldehyde (FA) based on in situ generation of fluorescent silver nanoclusters (AgNCs) was demonstrated by using modified Tollens’ reagent. Tollens’ reagent is a reagent commonly used to distinguish between aldehyde and ketone functional groups. A silver mirror will be observed on a test tube surface if the sample contains aldehyde groups. However, in this method, the Tollens’ reagent was modified with polymethacrylic acid (PMAA), which acts as a template to generate fluorescent AgNCs instead of a silver mirror upon reaction with FA. In the presence of FA, Tollens’ reagent will be converted to AgNCs and the fluorescent emissions can be recorded. The fluorescence intensity of the generated AgNCs linearly increased as a function of the FA concentration. Parameters that may affect the detection sensitivity were studied and optimized. The proposed method has excellence selectivity for the detection of FA over other compounds. The proposed strategy exhibited a linear working concentration range of 1.0–9.0 μM with a detection limit of 0.14 μM and can be efficiently used to detect FA in bean sprout samples with a satisfactory accuracy. This proposed method does not require a complicated sensor probe preparation and enhances the FA detection selectivity and sensitivity.

Poly(amine) modified kaolinite clay for VOC capture

Polyethylenimine (PEI) functionalized kaolinite clay was successfully prepared, characterized, and assessed for the remediation of volatile organic compounds (VOCs) comprising the aldehyde, carboxylic acid, and disulfide functional group classes. A gas chromatographic vapor capture assay evaluated the capability of unmodified and modified clay material to capture representative aldehyde, carboxylic acid, and disulfide VOCs in a laboratory setting. Unmodified kaolinite (Kao) clay was moderately or poorly effective at remediating these VOCs, while the poly(amine) functionalized Kao was capable of capturing VOCs in the vapor phase with reductions up to 100%. Sample cartridge tubes were packed with PEI-functionalized clay in order to assess their ability to reduce the detectable volatile fatty acid load at an open-air rendering plant in a relevant field test for applying these materials in a packed-bed scrubber application. The PEI-Kao packed cartridges were capable of significantly reducing the detectable concentration of volatile fatty acid effluent from the rendering operation. These volatile fatty acids are major contributors to nuisance odors associated with rendering.

Evaluation of Pre-Chlorinated Wastewater Effluent for Microalgal Cultivation and Biodiesel Production

Microalgae are promising feedstock to produce biodiesel and other value added products. However, the water footprint for producing microalgal biodiesel is enormous and would put a strain on the water resources of water stressed countries like South Africa if freshwater is used without recycling. This study evaluates the utilization of pre-chlorinated wastewater as a cheap growth media for microalgal biomass propagation with the aim of producing biodiesel whilst simultaneously remediating the wastewater. Wastewater was collected from two wastewater treatment plants (WWTPs) in Durban, inoculated with Neochloris aquatica and Asterarcys quadricellulare and the growth kinetics monitored for a period of 8 days. The physicochemical parameters; including chemical oxygen demand (COD), total nitrogen (TN), and total phosphorus (TP) were determined before microalgal cultivation and after harvesting. Total lipids were quantified gravimetrically after extraction by hexane/isopropanol (3:2 v/v). Biodiesel was produced by transesterification and characterised by gas chromatography. The total carbohydrate was extracted by acid hydrolysis and quantified by spectrophotometric method based on aldehyde functional group derivatization. Asterarcys quadricellulare utilized the wastewater for growth and reduced the COD of the wastewater effluent from the Umbilo WWTP by 12.4%. Total nitrogen (TN) and phosphorus (TP) were reduced by 48% and 50% respectively by Asterarcys quadricellulare cultivated in sterile wastewater while, Neochloris reduced the TP by 37% and TN by 29%. Although the highest biomass yield (460 mg dry weight) was obtained for Asterarcys, the highest amount of lipid (14.85 ± 1.63 mg L−1) and carbohydrate (14.84 ± 0.1 mg L−1) content were recorded in Neochloris aquatica. The dominant fatty acids in the microalgae were palmitic acid (C16:0), stearic acid (C18:0) and oleic acid (C18:1). The biodiesel produced was determined to be of good quality with high oxidation stability and low viscosity, and conformed to the American society for testing and materials (ASTM) guidelines.

Biodegradability of polyethylene by bacteria and fungi from Dandora dumpsite Nairobi-Kenya.

This study aimed at isolating and identifying bacteria and fungi with the capacity to degrade low density polyethylene (LDPE). The level of biodegradation of LDPE sheets with bacterial and fungal inoculums from different sampling points of Dandora dumpsite was evaluated under laboratory conditions. Incubation of the LDPE sheets was done for sixteen weeks at 37°C and 28°C for bacteria and fungi respectively in a shaker incubator. Isolation of effective candidates for biodegradation was done based on the recorded biodegradation outcomes. The extent of biodegradation on the polyethylene sheets was assessed by various techniques including weight loss analysis, Fourier Transform Infrared Spectroscopy (FTIR) and GC-MS. Fourier Transform Infra-Red spectroscopy (FTIR) analysis revealed the appearance of new functional groups attributed to hydrocarbon degradation after incubation with the bacteria and fungi. Analysis of the 16S rDNA and 18S rDNA sequences for bacteria and fungi respectively showed that bacteria belonging to genera Pseudomonas, Bacillus, Brevibacillus, Cellulosimicrobium, Lysinibacillus and fungi of genus Aspergillus were implicated as polyethylene degraders. An overall analysis confirmed that fungi are generally better degraders of polyethylene than bacteria. The highest fungal degradation activity was a mean weight reduction of 36.4±5.53% attributed to Aspergillus oryzae strain A5, 1 (MG779508). The highest degradation activity for bacteria was a mean of 35.72± 4.01% and 20.28± 2.30% attributed to Bacillus cereus strain A5,a (MG645264) and Brevibacillus borstelensis strain B2,2 (MG645267) respectively. Genus Aspergillus, Bacillus and Brevibacillus were confirmed to be good candidates for Low Density Poly Ethene bio-degradation. This was further confirmed by the appearance of the aldehyde, ether and carboxyl functional groups after FTIR analysis of the polythene sheets and the appearance of a ketone which is also an intermediary product in the culture media. To improve this degrading capacity through assessment of optimum conditions for microbial activity and enzyme production will enable these findings to be applied commercially and on a larger scale.

Identification of 2, 3-dihydrodipicolinate as the product of the dihydrodipicolinate synthase reaction from Escherichia coli

Dihydrodipicolinate synthase (DHDPS) catalyzes the first step in the pathway for the biosynthesis of L-lysine in most bacteria and plants. The substrates for the enzyme are pyruvate and L-aspartate-β-semialdehyde (ASA). The product of the reaction was originally proposed to be 2,3-dihydrodipicolinate (DHDP), but has now generally been assumed to be (4S)-4-hydroxy-2,3,4,5-tetrahydro-(2S)-dipicolinate (HTPA). ASA is unstable at high pH and it is proposed that ASA reacts with itself. At high pH ASA also reacts with Tris buffer and both reactions are largely reversible at low pH. It is proposed that the basic un-protonated form of the amine of Tris or the α-amine of ASA reacts with the aldehyde functional group of ASA to generate an imine product. Proton NMR spectra of ASA done at different pH values shows new NMR peaks at high pH, but not at low pH, confirming the presence of reaction products for ASA at high pH. The enzymatic product of the DHDPS reaction was examined at low pH by proton NMR starting with either 3 h-pyruvate or 3 d-pyruvate and identical NMR spectra were obtained with four new NMR peaks observed at 1.5, 2.3, 3.9 and 4.1 ppm in both cases. The NMR results were most consistent with DHDP as the reaction product. The UV-spectral studies of the DHDPS reaction shows the formation of an initial product with a broad spectral peak at 254 nM. The DHDPS reaction product was further examined by reduction of the enzymatic reaction components with borohydride followed by GC-MS analysis of the mixture. Three peaks were found at 88, 119 and 169 m/z, consistent with pyruvate, homoserine (reduction product of ASA), and the reduction product of DHDP (1,2,3,6-tetrahydropyridine-2,6-dicarboxylate). There was no indication for a peak associated with the reduced form of HTPA.

Surface characterisation and reaction kinetics of silver nanoparticles mediated by the leaf and flower extracts of French marigold (Tagetes patula).

In this study, French marigold's leaf and flower were used for the synthesis of silver nanoparticles (SNPs) in order to explore their potentials towards bioreduction of Ag+ to Agᵒ. The as-synthesised SNPs were characterised using UV-Vis spectroscopy, Fourier transform infrared (FTIR) spectroscopy, powder X-ray diffraction, transmission electron microscopy, and zeta-potential analysis. The results obtained showed that the particles are polydispersed with sizes in the range 15.8-42.8 nm. The bioreduction was believed to be due to the amides, aldehyde functional groups, and essential oils present in the extracts as confirmed by the FTIR analysis. The growth mechanism involved in the reaction was studied which revealed oriented attachment (OA) onwards Ostwald ripening in the case of the flower-mediated synthesis and typical OA in the leaf-mediated synthesis. The studied kinetics of the particle formation showed that the reaction is possibly a pseudo-first-order reaction with some diffusion-controlled mechanism which is driven by high surface area to volume ratio in both the leaf- and flower-mediated synthesis.

A Computational Mechanistic Investigation into Reduction of Gold(III) Complexes by Amino Acid Glycine: A New Variant for Amine Oxidation.

Density functional theory (DFT) was utilized to explore the reduction of gold(III) complexes by the amino acid glycine (Gly). Interestingly, when the nitrogen atom of Gly coordinates to the gold(III) center, its Cα -hydrogen atom becomes so acidic that it can be easily deprotonated by a mild base like water. The deprotonation converts the amino acid into a potent reductant by which gold(III) is reduced to gold(I) with a moderate activation energy. To our knowledge, this is the first contribution suggesting that primary amines are oxidized to imines via direct α-carbon deprotonation. This finding may provide new insights into the mechanistic interpretation of amine oxidations catalyzed/mediated by a center with high cathodic reduction potential. This work also provides a rationalization behind why gold(III) complexes with amine-based polydentate ligands are reluctant to undergo a redox process. Gold(III) reduction occurs most efficiently if the Cα proton leaves in the plane of the Cα , N and Au atoms. Chelation prevents this alignment, resulting in the gold(III) complex being unreactive toward reduction. It has been experimentally found that gold(III) is capable of oxidizing Gly to glyoxylic acid (GA) as the initial product. The latter, in the presence of another gold(III) complex, has been reported to undergo oxidative decarboxylation to afford CO2 and HCOOH. This process is found to be mediated by formation of a geminal diol intermediate produced by reaction of water with the aldehyde functional group of the coordinated GA.

Monitoring glucose, calcium, and magnesium levels in saliva as a non-invasive analysis by sequential injection multi-parametric determination

The use of saliva for diagnose and surveillance of systemic illnesses, and general health has been arousing great interest worldwide, emerging as a highly desirable goal in healthcare. The collection is non-invasive, stress-free, inexpensive, and simple representing a major asset. Glucose, calcium, and magnesium concentration are three major parameters evaluated in clinical context due to their essential role in a wide range of biochemical reactions, and consequently many health disorders. In this work, a spectrophotometric sequential injection method is described for the fast screening of glucose, calcium, and magnesium in saliva samples. The glucose determination reaction involves the oxidation of the aldehyde functional group present in glucose with simultaneous reduction of 3,5-dinitrosalicylic acid (DNS) to 3-amino, 5-nitrosalicylic acid under alkaline conditions, followed by the development of colour. The determination of both metals is based on their reaction with cresolphtalein complexone (CPC), and the interference of calcium in the magnesium determination minimized by ethylene glycol-bis[β-aminoethyl ether]-N,N,N′,N′-tetraacetic acid (EGTA). The developed multi-parametric method enabled dynamic ranges of 50 – 300 mg/dL for glucose, 0.1 − 2 mg/dL for calcium, and 0.1 − 0.5 mg/dL for magnesium. Determination rates of 28, 60, 52 h−1 were achieved for glucose, calcium, and magnesium, respectively. Less than 300 µL of saliva is required for the multi-parametric determination due to saliva viscosity and inherent necessity of dilution prior to analysis. RSDs lower than 5% were obtained, and the results agreed with those obtained by reference methods, while recovery tests confirmed its accuracy.

Synthesis and Characterization of Novel Modified and Functionalized Silica Nano-particles for Protein Delivery Applications

In this study, the synthesis, characterization and controlled release behavior of new Hollow Silica Nano particles (HSNPs) and Magnetic Silica Nano Particles (MSNPs) were studied. Magnetic Silica Nano particles (MSNPs), as drug delivery vehicles, were synthesized through the coating of Fe3O4 nano-crystals with silica layers. The HSNPs were obtained by removal of Fe3O4 templates with hydrochloric acid and then calcinated at the high temperature. In the first step, MSNPs and HSNPs were modified and the amine and aldehyde functional groups were introduced on the silica surfaces. In the next step, positively charged silica nano particles were synthesized through the quaternization of Aminated Silica Nano Particles (ASNP) with sodium monochloroacetate (SMCA). Following characterization, insulin was loaded into the nano particles as a model system which demonstrated a notable sustained drug release. The study shows that the HSNPs could load a higher amount of drug. The release rates from the HSNPs were faster than those of MSNPs.

Dome C ultracarbonaceous Antarctic micrometeorites

Context.UltraCarbonaceous Antarctic MicroMeteorites (UCAMMs) represent a small fraction of interplanetary dust particles reaching the Earth’s surface and contain large amounts of an organic component not found elsewhere. They are most probably sampling a contribution from the outer regions of the solar system to the local interplanetary dust particle (IDP) flux.Aims.We characterize UCAMMs composition focusing on the organic matter, and compare the results to the insoluble organic matter (IOM) from primitive meteorites, IDPs, and the Earth.Methods.We acquired synchrotron infrared microspectroscopy (μFTIR) andμRaman spectra of eight UCAMMs from the Concordia/CSNSM collection, as well as N/C atomic ratios determined with an electron microprobe.Results.The spectra are dominated by an organic component with a low aliphatic CH versus aromatic C=C ratio, and a higher nitrogen fraction and lower oxygen fraction compared to carbonaceous chondrites and IDPs. The UCAMMs carbonyl absorption band is in agreement with a ketone or aldehyde functional group. Some of the IR and Raman spectra show a C≡N band corresponding to a nitrile. The absorption band profile from 1400 to 1100 cm-1is compatible with the presence of C-N bondings in the carbonaceous network, and is spectrally different from that reported in meteorite IOM. We confirm that the silicate-to-carbon content in UCAMMs is well below that reported in IDPs and meteorites. Together with the high nitrogen abundance relative to carbon building the organic matter matrix, the most likely scenario for the formation of UCAMMs occurs via physicochemical mechanisms taking place in a cold nitrogen rich environment, like the surface of icy parent bodies in the outer solar system. The composition of UCAMMs provides an additional hint of the presence of a heliocentric positive gradient in the C/Si and N/C abundance ratios in the solar system protoplanetary disc evolution.