Optimizing reaction conditions for the light-driven hydrogen evolution in a loop photoreactor

• Pengcheng Li,
• Daniel Kowalczyk,
• Johannes Liessem,
• Mohamed M. Elnagar,
• Dariusz Mitoraj,
• Radim Beranek and
• Dirk Ziegenbalg

Beilstein J. Org. Chem. 2024, 20, 74–91, doi:10.3762/bjoc.20.9

• the synthesis of the photocatalyst, melamine (99%, Sigma-Aldrich), H2PtCl6·6H2O (with a minimum Pt content of 37.50%, Sigma-Aldrich), and methanol (99.9%, VWR) were utilized. The heptazine-based polymeric carbon nitride (PCN) was synthesized by thermally condensing 30 g of melamine at 550 °C for 4 h

Mechanochemical bottom-up synthesis of phosphorus-linked, heptazine-based carbon nitrides using sodium phosphide

• Blaine G. Fiss,
• Georgia Douglas,
• Michael Ferguson,
• Jorge Becerra,
• Jesus Valdez,
• Trong-On Do,
• Tomislav Friščić and
• Audrey Moores

Beilstein J. Org. Chem. 2022, 18, 1203–1209, doi:10.3762/bjoc.18.125

•  1, Figure S5a, blue trace) and g-h-PCN300 (Figure S5a, green) was investigated by diffuse reflectance spectroscopy (DRS), and compared to that of a pure g-CN sample made by annealing melamine in a loosely capped alumina crucible at 550 °C for 4 hours, with a ramp rate of 5 °C min−1 [49]. The g-CN

Study on the interactions between melamine-cored Schiff bases with cucurbit[n]urils of different sizes and its application in detecting silver ions

• Jun-Xian Gou,
• Yang Luo,
• Xi-Nan Yang,
• Wei Zhang,
• Ji-Hong Lu,
• Zhu Tao and
• Xin Xiao

Beilstein J. Org. Chem. 2021, 17, 2950–2958, doi:10.3762/bjoc.17.204

• constructed by three different cucurbiturils and synthesized by guest melamine-cored Schiff bases (TBT) through outer-surface interaction and host–guest interactions. TBT forms a TMeQ[6]-TBT complex with TMeQ[6] through outer-surface interaction, while Q[7]-TBT and Q[8]-TBT form complexes with Q[7,8] through

• host–guest interactions. Among them, Q[7]-TBT is selected as a UV detector for the detection of silver ions (Ag+). This work makes full use of the characteristics of each cucurbituril and melamine-cored Schiff base to construct a series of complexes and these are applied to metal detection. Keywords

• : cucurbiturils; melamine; Schiff base; silver ion; Introduction Schiff bases [1] are usually synthesized by the condensation of amines and active carbonyl compounds, endowing them both nitrogen and oxygen donor atoms [2][3][4][5]. Schiff bases are not only easy to coordinate with various transition metal ions

Chemical approaches to discover the full potential of peptide nucleic acids in biomedical applications

• Nikita Brodyagin,
• Martins Katkevics,
• Venubabu Kotikam,
• Christopher A. Ryan and
• Eriks Rozners

Beilstein J. Org. Chem. 2021, 17, 1641–1688, doi:10.3762/bjoc.17.116

• matched DNA duplex [136]. Bong and co-workers used melamine as a Janus-wedge nucleobase (KM, Figure 9) to organize two identical strands of oligothymidine DNA tracts (or oligouridine RNA tracts) on a peptide template to form peptide−DNA(RNA) triplex structures [137]. This approach was applied to induce

Photoinduced post-modification of graphitic carbon nitride-embedded hydrogels: synthesis of 'hydrophobic hydrogels' and pore substructuring

• Cansu Esen and
• Baris Kumru

Beilstein J. Org. Chem. 2021, 17, 1323–1334, doi:10.3762/bjoc.17.92

• of this study, which is divided into two parts, the hydrogel denoted as HGCM was utilized as the main substrate for both sections. To prepare HGCM, firstly graphitic carbon nitride was synthesized from the thermal treatment of a cyanuric acid–melamine supramolecular complex (CM) [42]. The resulting

• % aqueous solution, Merck), magnesium chloride (MgCl2, 99%, Merck), melamine (99%, Sigma-Aldrich), poly(ethylene glycol) dimethacrylate (PEGDMA, Mn 550, Sigma-Aldrich), poly(ethylene glycol) methyl ether methacrylate (PEGMEMA, Mn 300, Sigma-Aldrich), potassium chloride (KCl, 99%, Merck), rhodamine B (RhB

• , 95%, Sigma-Aldrich), sodium chloride (NaCl, 99%, Sigma-Aldrich), sodium hydroxide (1 M solution, Sigma-Aldrich). DMA, PEGDMA, PEGMEMA and were passed through basic alumina column prior to use. Synthesis of g-CN: g-CN was synthesized from cyanuric acid–melamine supramolecular complex as reported in

Synthetic accesses to biguanide compounds

• Oleksandr Grytsai,
• Cyril Ronco and
• Rachid Benhida

Beilstein J. Org. Chem. 2021, 17, 1001–1040, doi:10.3762/bjoc.17.82

• degradation occurs leading to melamine derivatives via loss of ammonia. Hydrochloride and sulfate salts were shown to be more stable. The spectroscopic properties of biguanide are well documented [2]: neutral biguanide presents a maximum of absorption at 234 nm in UV spectrometry corresponding to the π–π

• example, in line with the previous example, Kurzer and Pitchfork already reported as early as 1964, the reaction of biguanides and carbodiimides in DMF at 100 °C to prepare mono- and disubstituted melamine, and trisubstituted isomelamine derivatives (Scheme 44A) [83]. Later, the same authors described the

Heterogeneous photocatalysis in flow chemical reactors

• Christopher G. Thomson,
• Ai-Lan Lee and
• Filipe Vilela

Beilstein J. Org. Chem. 2020, 16, 1495–1549, doi:10.3762/bjoc.16.125

A systematic review on silica-, carbon-, and magnetic materials-supported copper species as efficient heterogeneous nanocatalysts in “click” reactions

• Pezhman Shiri and
• Jasem Aboonajmi

Beilstein J. Org. Chem. 2020, 16, 551–586, doi:10.3762/bjoc.16.52

• loss of catalytic activity. Using a multistep solid-phase procedure, Shantz et al. reported on SBA-15 functionalized with melamine-based dendrons (Scheme 3) [27]. The Cu and Cu/Au nanoparticles were then supported on this new composite to generate a nanocatalyst. The catalytic application of this

Carbazole-functionalized hyper-cross-linked polymers for CO₂ uptake based on Friedel–Crafts polymerization on 9-phenylcarbazole

• Dandan Fang,
• Xiaodong Li,
• Meishuai Zou,
• Xiaoyan Guo and
• Aijuan Zhang

Beilstein J. Org. Chem. 2019, 15, 2856–2863, doi:10.3762/bjoc.15.279

• wt %) at 1.0 bar/273 K. which was higher than that of the carbazole-based microporous polymers PBT-C1 (46 cm3 g−1) [26], CMPSO-1B3 (46.8 cm3 g−1) [24], CPOP2-4 (7.8–9.0 wt %) [19], tetraphenylmethane-based CPOP10 (SBET = 3337 m2 g−1, 9.1 wt %, at 298 K/1.00 bar) [45] or the melamine-based microporous

Design, synthesis and structure of novel G-2 melamine-based dendrimers incorporating 4-(n-octyloxy)aniline as a peripheral unit

• Cristina Morar,
• Pedro Lameiras,
• Attila Bende,
• Gabriel Katona,
• Emese Gál and
• Mircea Darabantu

Beilstein J. Org. Chem. 2018, 14, 1704–1722, doi:10.3762/bjoc.14.145

• from 4-(n-octyloxy)aniline, seven G-2 melamine-based dendrimers were obtained in 29–79% overall yields. Their iterative convergent- and chemoselective synthesis consisted of SN2-Ar aminations of cyanuric chloride and final triple N-acylations and Williamson etherifications (→ G-2 covalent trimers) or

• step-by-step structural elucidation of novel G-2 melamine dendrimers based on 4-(n-octyloxy)aniline are reported. Our study demonstrates the crucial influence of the nature (covalent vs ionic) of the dendritic construction in tandem with that of its central building blocks on the aptitude of dendrimers

• to self-organise in solution and to self-assembly in the solid state. Keywords: amination; dendrimers; melamines; nano-aggregates; 4-(n-octyloxy)aniline; Introduction N-Substituted melamine (2,4,6-triamino-1,3,5-triazine)-based dendrimers are a class of macromolecules reported as early as 2000 by E

A journey in bioinspired supramolecular chemistry: from molecular tweezers to small molecules that target myotonic dystrophy

• Steven C. Zimmerman

Beilstein J. Org. Chem. 2016, 12, 125–138, doi:10.3762/bjoc.12.14

• use of a melamine (2,4,6-triamino-1,3,5-triazine) unit for formation of a base-triplet, as shown in Figure 8b. Additional reports by Lehn [78] and McLaughlin [79] supported this approach and the melamine unit has more recently been used extensively by Bong [80]. So why did we once again become

Atherton–Todd reaction: mechanism, scope and applications

• Stéphanie S. Le Corre,
• Mathieu Berchel,
• Hélène Couthon-Gourvès,
• Jean-Pierre Haelters and
• Paul-Alain Jaffrès

Beilstein J. Org. Chem. 2014, 10, 1166–1196, doi:10.3762/bjoc.10.117

• effects. Melamine polyphosphate (MPP, Scheme 34), illustrates this possibility: melamine decomposes endothermically and produces NH3 when burning (a gas-phase active agent), while polyphosphate, which is simultaneously produced, favors the charring process. The synergic effects of phosphorus and nitrogen

Silica sulfuric acid: a reusable solid catalyst for one pot synthesis of densely substituted pyrrole-fused isocoumarins under solvent-free conditions

• Sudipta Pathak,
• Kamalesh Debnath and
• Animesh Pramanik

Beilstein J. Org. Chem. 2013, 9, 2344–2353, doi:10.3762/bjoc.9.269

• chemical processes. Hence, we have carried out the synthesis by dissolving the substrate 7 and aniline in a minimum volume of chloroform, soaked them on the solid surface of solid Brønsted acid catalysts, such as silica gel and melamine sulfonic acid (MSA), dried the mixture under vacuum, and heated the

Damage of polyesters by the atmospheric free radical oxidant NO₃^•: a product study involving model systems

• Catrin Goeschen and
• Uta Wille

Beilstein J. Org. Chem. 2013, 9, 1907–1916, doi:10.3762/bjoc.9.225

• degradation of high-performing polyesters under environmental conditions. It is obvious that detailed kinetic data and product analyses from exposure studies involving both simple as well as more complex model systems, including melamine cross-linker moieties, are required (for example from smog chamber

Synthesis of dye/fluorescent functionalized dendrons based on cyclotriphosphazene

• Aurélien Hameau,
• Sabine Fuchs,
• Régis Laurent,
• Jean-Pierre Majoral and
• Anne-Marie Caminade

Beilstein J. Org. Chem. 2011, 7, 1577–1583, doi:10.3762/bjoc.7.186

• grafted as terminal groups on to dendrimers. In particular the dansyl group has been frequently used to functionalize poly(propyleneimine) [7][8], poly(lysine) [9], poly(amidoamine) [10], and poly(melamine) [11] dendrimers. It has been shown that no interaction occurs between these terminal fluorophores

A hydrogen- bonded channel structure formed by a complex of uracil and melamine

• Reji Thomas and
• G. U. Kulkarni

Beilstein J. Org. Chem. 2007, 3, No. 17, doi:10.1186/1860-5397-3-17

• Reji Thomas G. U. Kulkarni Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur (P.O), Bangalore – 560064, India 10.1186/1860-5397-3-17 Abstract The structure of a 1:1 complex of uracil and melamine obtained by cocrystallization has been

• investigated. The structure involves hydrogen bonded layers with apertures stacked along the a and b directions giving rise to channels, unlike the complex of cyanuric acid with melamine. Background Hydrogen bonded organic structures have emerged to become an important area of research because of the wide

• variety of fascinating structural features as well as properties exhibited by them. Of the many interesting hydrogen bonded systems, those formed by cyanuric acid and melamine are specially interesting. Thus, cyanuric acid forms hydrogen bonded adducts with melamine, [1] 4,4'-bipyridyl [2] and 4,4