ChemMend: A Card Game To Introduce and Explore the Periodic Table while Engaging Students’ Interest

The deeply knowledge of the periodic table is one of the most important keys to understand the basic principles of Chemistry. Memorizing the elements of the groups and periods is one of the most commonly used strategies to learn the position of each element in the periodic table; nevertheless it is a hard task for most students. The use of card games can represent a useful alternative to teach some chemical aspects. Here, we present ChemMend, a new Chemical card game which will allow chemistry students to obtain a good ability in the periodic table. This game attracts the attention of the students, and it allows them to review mentally the period and group while playing; being the learning a consequence of the game. The ChemMend game will introduce and explore the periodic table in the classroom

Host–Guest chemistry of self-assembled hemi-cage systems: The dramatic effect of lost pre-organization

New hemi‐cage compounds with the formula Pd2(L1)2(L2)2 (L1=ditopic pyridine ligand, L2=bpy or TMEDA) have been synthesized and characterized by spectroscopic methods, X‐ray crystallography and electronic structure methods. The host‐guest chemistry of these new structures, with naphthoquinone as a guest, reveals the key role of the host shape and flexibility on competitive binding processes. The influence of counteranions, solvent and non‐covalent interactions to binding were quantified by Density Functional Theory calculations. Together, this study provides new insights into the concept of pre‐organized guest binding when applied to charged, coordination‐assembled hosts

Macrocycle Synthesis by Chloride-Templated Amide Bond Formation

A new family of pseudopeptidic macrocyclic compounds has been prepared involving an anion-templated amide bond formation reaction at the macrocyclization step. Chloride anion was found to be the most efficient template in the macrocyclization process, producing improved macrocyclization yields with regard to the nontemplated reaction. The data suggest a kinetic effect of the chloride template, providing an appropriate folded conformation of the openchain precursor and reducing the energy barrier for the formation of the macrocyclic product.This work was supported by the Spanish Ministry of Science and Innovation (CTQ2012-38543-C03) and Generalitat Valenciana (PROMETEO/2012/020). V.M.-C. thanks Generalitat Valenciana for a postdoctoral fellowship (APOSTD/ 2013/041)

Kinetic Analysis for Macrocyclizations Involving Anionic Template at the Transition State

Several kinetic models for the macrocyclization of a C2 pseudopeptide with a dihalide through a SN2 reaction have been developed. These models not only focus on the kinetic analysis of the main macrocyclization reaction, but also consider the competitive oligomerization/polymerization processes yielding undesired oligomeric/polymeric byproducts. The effect of anions has also been included in the kinetic models, as they can act as catalytic templates in the transition state reducing and stabilizing the transition state. The corresponding differential equation systems for each kinetic model can be solved numerically. Through a comprehensive analysis of these results, it is possible to obtain a better understanding of the different parameters that are involved in the macrocyclization reaction mechanism and to develop strategies for the optimization of the desired processes

Synthesis and Crystal Structure of 6-Bromo-2-(furan-2-yl)-3-(prop-2-ynyl)-3H-imidazo[4,5-b]pyridine

The crystal and molecular structure of 6-bromo-2-(furan-2-yl)-3-(prop-2-ynyl)-3H-imidazo[4,5-b]pyridine (C13H8BrN3O) has been investigated from single crystal X-ray diffraction data. The primary focus is to investigate the molecular geometry of this compound in the solid state along with the associated intermolecular hydrogen bonding and related π-π interactions present in the crystal packing. This compound crystallizes in the monoclinic space group with cell parameters: a = 4.39655(19) Å, b = 13.5720(5) Å, c = 20.0471(5) Å, β = 94.753(3), V = 1192.10(7) Å3, D = 1.683 g·cm−3, and Z = 4. The crystal structure is stabilized by π-π interactions and intermolecular C–H⋯N and C–H⋯O interactions

Pseudopeptidic Compounds for Biocompatible Gels: A Review

Simple pseudopeptides derived from natural amino acids can be designed and prepared as efficient gelators for a variety of solvents, and with a high potential for biocompatibility. The appropriate selection of structural components, reviewed herein, shows how to produce gels with tailored properties, including high thermal stability

Macrocyclization Reactions: The Importance of Conformational, Configurational, and Template-Induced Preorganization

The success of a given macrocyclization reaction involves a very delicate balance of many different factors. First, a proper understanding of the basic thermodynamic and kinetic concepts underlying these processes is essential in defining the strategies to obtain the targeted cyclic structures and the experimental elements to be optimized. essential element for achieving high yields in a macrocyclization process is the appropriate selection of the disconnection site. This defines the reaction used for the key step, which will clearly affect the overall process, but also delineates the nature and structure of the immediate linear precursor. The presence of structural elements, including configurational elements, able to induce a favorable folding of this linear precursor in such a way that both reactive ends approach with the proper orientation provides significant enhancements in macrocyclizations. The use of templates of very different natures is a versatile strategy to overcome the limitations of the other macrocyclization strategies. The use of templates has allowed the preparation of a variety of macrocyclic structures in better yields and usually in shorter reaction times, and often allows easier purification protocols.Financial support of the Spanish Ministry of Science and Innovation (CTQ2012-38543-C03) and Generalitat Valenciana (PROMETEO/2012/020) is acknowledged. V.M.-C. thanks the Spanish Ministry of Science and Education for a predoctoral fellowship (FPU AP2007-02562) and Generalitat Valenciana for a VALi+d postdoctoral fellowship (APOSTD/2013/041). M.D.P. thanks the Spanish Ministry of Education for a postdoctoral fellowship and UGC India for a Startup Grant

Underwater Multirobot Cooperative Intervention MAC Protocol

This work introduces a Medium Access Control (MAC) protocol designed to allow a group of underwater robots that share a wireless communication channel to effectively communicate with each other. The goal of the Underwater Multirobot Cooperative Intervention MAC (UMCI-MAC) protocol presented in this work is to minimize the end to end delay and the jitter. The access to the medium in UMCI-MAC follows a Time Division Multiple Access (TDMA) strategy which is arbitrated by a master, which also has the capability to prioritize the transmission of some nodes over the rest of the network. Two experiments have been carried out with a team of four Autonomous Underwater Vehicles (AUV) in order to compare this protocol with Aloha-CS and S-FAMA MAC protocols used in Underwater Wireless Sensor Networks (UWSN). In the first experiment, the communications and the AUVs have been simulated using UWSim-NET. The objective of this experiment was to evaluate all three protocols in terms of delay, jitter, efficiency, collisions and throughput depending on the size of the data packet and the rate of packet delivery in the application layer for each robot. The results of this experiment proved that UMCI-MAC successfully avoids packet collisions and outperforms the other two protocols in terms of delay, jitter and efficiency. The second experiment consisted of a Hardware In The Loop (HIL) teleoperation of a team of four robots. One of the AUVs was a real BlueROV in a water tank, while the remaining AUVs and the communications were simulated with UWSim-NET. It demonstrates the impact of the MAC protocols in underwater acoustic links. Of the three MAC protocols evaluated in this work, UMCI-MAC was the only one which succeeded in the proposed teleoperation experiment. Thus demonstrating its suitability as a communications protocol in underwater cooperative robotics

Cu2+ recognition by N,N′-benzylated bis(amino amides)

Two new C 2 -symmetric N , N ’ -benzylated bis(amino amides) have been synthesised and their interaction with di ff erent transition metals studied using a variety of techniques including UV-Vis and CD spec- troscopy or ESI-MS. The determination of the corresponding stability constants with Cu 2+ has been possi- ble, in H 2 O/CH 3 CN 7/3 v/v, for one of these ligands ( 4 ) using potentiometric titrations. The results obtained reveal that N -benzylation a ff ords signi fi cant changes to their properties and is accompanied by an appreciable decrease in the corresponding complexation stability constants. However, this, along with the low kinetics associated to Ni 2+ , facilitates the recognition of Cu 2+ by 4 that can be followed by the naked-eye up to the submillimolar range. Very interestingly, the chiral nature of this ligand provides an intense and well de fi ned CD curve for the corresponding Cu 2+ complex, very sensitive to the coordination geometry, facilitating the analysis of this interaction even at the μ M range. The formation by both ligands ( 3 and 4 ) of square planar complexes with Cu 2+ and Ni 2+ displaying a 1 : 1 stoichiometry was con fi rmed by their X-ray crystal structuresFinancial support from Spanish MINECO (CTQ2015-68429-R), Generalitat Valenciana (PROMETEO/2016/071) and PPI-UJI (P1-1B-2013-38) is gratefully acknowledged. L. G. thanks Generalitat Valenciana for a Grisolia fellowship (GRISOLIA 2012/015)