Polycyclic tetraazamacrocycles

V průběhu práce by|y připraveny dvě série nových biryk|iclcých tetraazamakrocyk|ů, v jejichžstrukturách se objevuje motiv !,5,8,I2- tetraazabiryklo[10.2.2]hexadekanu(l,4-en-ryklamu)1a1,4,8,1l-tetraazabi- cyk|o[6.6'2]hexadekanu (1,8-en-ryklamu) 8. Při přípravě s|oučenin odvozených od 1,4-en-cyklamu by|o využito ma|é rozpustnosti kvafterní ammoniové so|i 2 v nepo|árních rozpouštěd|ech, díky nž.by|o možnéprovedení substituce makroryk|u pouze na jediném atomu dusíku. U připravených |igandů 3 a 6 by|y pozorovány komp|exotvorné v|astnosti, které odpovída|y předpok|ádanému chování těchto |átek, En. by| pozorován vznik komp|exů s ioný mědi a zinku a pomocí potenciometriclcých stanovení by|y určeny termodynamické konstanty stabi|iý těchto komp|exů. Hodnoý těchto konstant by|y nižšínež u ana|ogicých monoryk|iclcých Iigandů (cyk|amu a N,N',N'',N'''-tetramethy|- ryk|amu) zřejmě z důvodu energetické nevýhodnosti změny konformace piperazinového kruhu (strukturní podjednotlcy makroryklu) mezi |igandem ve 'vo|ném. stavu a |igandem koordinovaným na atom kovu. Jsou-|i však mezi sebou porovnávány hodnoý konstant stabi|iý dvojic cyk|am - N,N.,N..,N'''- tetramethy|cyk|am a |igand 1 - |igand 3 zjistíme, žetrendy změn hodnot těchto konstant jsou u obou skupin přib|ižně steiné (pok|es o přib|ižně 10 řádů směrem od méně...Two series of new bicyclic tetraazamacrorycles built up on skeletons of either 1,5,8,12-tetraazabiryclo[10.2.2]hexadecane (1,4-en-cyclam) I or 1,4,8,11- tetraazabicyclo[6.6.2]hexadecane (1,8-en-ryclam) 8 were prepared. The 1,4- en.cyc|am-based unsymmetrica| compounds bearing the pnitrobenzy| moieý (precursor for a biomolecule-conjugation) were synthesised exploiting the low so|ubi|iý of the intermediate quaternary derivative 2 in non-po|ar so|vents. The |igands 3 and 6 exhibited the expeďed comp|exing abi|ity towards copper(Il) and zinc(Il) although the complexation proceeded relatively slowly (at room temperature in order of hours). The mďa| comp|exes thus formed exhibited thermodynamic stability constants lower than those repofted for similar monoryclic tetraazamacrocycles (cyclam, Me+cyclam) probably due to inadvisability of the conformational change (chair or twisted-boat -> boat conformation of the piperazine subunit) conneďed to the metaI ion encapsulation. On the other hand, when the stability of coppe(Il) complex of 3 is compared to stabi|iý constant reported for the biryc|ic amine 1, the trend in the values of these constants is the same for the couple ligand I - ligand 3 as for the couple cyclam - Me+cyclam. During the attempted synthesis of the monoacetate ligand 5a an unusual reaction behaviour...Katedra anorganické chemieDepartment of Inorganic ChemistryPřírodovědecká fakultaFaculty of Scienc

Six-Degree-of-Freedom Steerable Visible-Light-Driven Microsubmarines Using Water as a Fuel: Application for Explosives Decontamination

Micro/nanomotors are capable of a wide variety of tasks related, i.e., to biomedical or environmental applications. Light-driven semiconductor-based micromotors are especially appealing, as they can split surrounding water via light irradiation, and therefore, they can move infinitely. However, their motion is typically limited to in-plane motion with four degrees of freedom (4DoF) or even pseudo-1D motion with 2DoF. Herein, magnetically steerable tubular TiO2/Fe3O4/CdS micromotors, termed microsubmarines, with 6DoF motion, based on a fuel-free design where surrounding water acts as fuel upon visible light irradiation, are presented, with an average velocity of 7.9 mu m s(-1). Besides, the generation of radicals via such water splitting aids the photocatalytic chemicals degradation with the potential to use solar radiation. A light-induced self-electrophoretic mechanism is responsible for the self-propulsion and can be used to predict the motion direction based on the structure and composition. Finally, the TiO2/Fe3O4/CdS microsubmarines are tested in a proof-of-concept application of high-energy explosive, e.g., picric acid, photocatalytic degradation, with the best performance owing to the versatility of 6DoF motion, the surface coating with amorphous TiO2 layer, and UV light. The results can help optimize light-active micromotor design for potential national security and environmental application, hydrogen evolution, and target cargo delivery

Chemical Microrobots as Self-Propelled Microbrushes against Dental Biofilm

Mouths offer the perfect environments for microbial cell formation, promoting the growth of biofilms, for example, on teeth. Dental biofilm exhibits strong resistance to antibiotics and is a cause of many dental diseases. Common strategies for dental biofilm removal involve the addition of high concentrations of hydrogen peroxide (H2O2), which increases tooth sensitivity, or mechanical procedures. Here, we report a different approach based on self-propelled micromachines with high antibacterial activity for the degradation of dental biofilm. Such microrobots use low concentrations of fuel for their propulsion, and they achieve an efficient dental biofilm disruption in only 5 min of treatment. Moreover, these microrobots are biocompatible with epidermal and organ cells and may stimulate the immune system to fight against microbial infection. This approach of exploiting the active motion of bubble-propelled catalytic micromachines for oral biofilm disruption may open the door for more efficient and sophisticated treatments in dentistry

Polycyclic tetraazamacrocycles

Two series of new bicyclic tetraazamacrorycles built up on skeletons of either 1,5,8,12-tetraazabiryclo[10.2.2]hexadecane (1,4-en-cyclam) I or 1,4,8,11- tetraazabicyclo[6.6.2]hexadecane (1,8-en-ryclam) 8 were prepared. The 1,4- en.cyc|am-based unsymmetrica| compounds bearing the pnitrobenzy| moieý (precursor for a biomolecule-conjugation) were synthesised exploiting the low so|ubi|iý of the intermediate quaternary derivative 2 in non-po|ar so|vents. The |igands 3 and 6 exhibited the expeďed comp|exing abi|ity towards copper(Il) and zinc(Il) although the complexation proceeded relatively slowly (at room temperature in order of hours). The mďa| comp|exes thus formed exhibited thermodynamic stability constants lower than those repofted for similar monoryclic tetraazamacrocycles (cyclam, Me+cyclam) probably due to inadvisability of the conformational change (chair or twisted-boat -> boat conformation of the piperazine subunit) conneďed to the metaI ion encapsulation. On the other hand, when the stability of coppe(Il) complex of 3 is compared to stabi|iý constant reported for the biryc|ic amine 1, the trend in the values of these constants is the same for the couple ligand I - ligand 3 as for the couple cyclam - Me+cyclam. During the attempted synthesis of the monoacetate ligand 5a an unusual reaction behaviour..

Polycyclic tetraazamacrocycles

Two series of new bicyclic tetraazamacrorycles built up on skeletons of either 1,5,8,12-tetraazabiryclo[10.2.2]hexadecane (1,4-en-cyclam) I or 1,4,8,11- tetraazabicyclo[6.6.2]hexadecane (1,8-en-ryclam) 8 were prepared. The 1,4- en.cyc|am-based unsymmetrica| compounds bearing the pnitrobenzy| moieý (precursor for a biomolecule-conjugation) were synthesised exploiting the low so|ubi|iý of the intermediate quaternary derivative 2 in non-po|ar so|vents. The |igands 3 and 6 exhibited the expeďed comp|exing abi|ity towards copper(Il) and zinc(Il) although the complexation proceeded relatively slowly (at room temperature in order of hours). The mďa| comp|exes thus formed exhibited thermodynamic stability constants lower than those repofted for similar monoryclic tetraazamacrocycles (cyclam, Me+cyclam) probably due to inadvisability of the conformational change (chair or twisted-boat -> boat conformation of the piperazine subunit) conneďed to the metaI ion encapsulation. On the other hand, when the stability of coppe(Il) complex of 3 is compared to stabi|iý constant reported for the biryc|ic amine 1, the trend in the values of these constants is the same for the couple ligand I - ligand 3 as for the couple cyclam - Me+cyclam. During the attempted synthesis of the monoacetate ligand 5a an unusual reaction behaviour..

Layered black phosphorus as a reducing agent - decoration with group 10 elements

Black phosphorus is prone to surface oxidation under ambient conditions. This attribute is often seen as a negative property of this interesting material. However, its proneness to oxidation - thus the reductive properties - can also be employed in modification of its surface and in preparation of composite materials. Here we describe the process of decoration of BP particles with nickel, palladium and platinum in form of a phosphide or in metallic form, respectively. The deposits have forms of films or nanoparticles and the reported method represents a general way of modifying the surface of black phosphorus with metals or their respective compounds for desired applications

Mechanism of Surface Alkylation of a Gold Aerogel with Tetra-n-butylstannane-d36

The formation of self-assembled monolayers on surfaces is often likely to be accompanied by the formation of byproducts, whose identification holds clues to the reaction mechanism but is difficult due to the minute amounts produced. We now report a successful identification of self-assembly byproducts using gold aerogel with a large specific surface area, a procedure likely to be applicable generally. Like a thin gold layer on a flat substrate, the aerogel surface is alkylated with n-butyl-d9 groups upon treatment with a solution of tetra-n-butylstannane-d36 under ambient conditions. The reaction byproducts accumulate in the mother liquor in amounts sufficient for GC-MS analysis. In chloroform solvent, they are butene-d8, butane-d10, octane-d18, and tributylchlorostannane-d27. In hexane, they are the same except that tributylchlorostannane-d27 is replaced with hexabutyldistannane-d54. The results are compatible with an initial homolytic dissociation of a C-Sn bond on the gold surface, followed by known radical processes

Mechanism of Surface Alkylation of a Gold Aerogel with Tetra‑<i>n</i>‑butylstannane‑<i>d</i>₃₆: Identification of Byproducts

The formation of self-assembled monolayers on surfaces is often likely to be accompanied by the formation of byproducts, whose identification holds clues to the reaction mechanism but is difficult due to the minute amounts produced. We now report a successful identification of self-assembly byproducts using gold aerogel with a large specific surface area, a procedure likely to be applicable generally. Like a thin gold layer on a flat substrate, the aerogel surface is alkylated with <i>n</i>-butyl-<i>d</i>₉ groups upon treatment with a solution of tetra-<i>n</i>-butylstannane-<i>d</i>₃₆ under ambient conditions. The reaction byproducts accumulate in the mother liquor in amounts sufficient for GC-MS analysis. In chloroform solvent, they are butene-<i>d</i>₈, butane-<i>d</i>₁₀, octane-<i>d</i>₁₈, and tributylchlorostannane-<i>d</i>₂₇. In hexane, they are the same except that tributylchlorostannane-<i>d</i>₂₇ is replaced with hexabutyldistannane-<i>d</i>₅₄. The results are compatible with an initial homolytic dissociation of a C–Sn bond on the gold surface, followed by known radical processes