Structural Preferences of Hydrogen-Bonded Networks in Organic Solution - the Cyclic CA3.cntdot.M3 "Rosette"

Mathias, John P.; Simanek, Eric E.; Zerkowski, Jonathan A.; Seto, Christopher T.; Whitesides, George M.

doi:10.1021/ja00089a021

Cited by 191 publications

(143 citation statements)

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“…[16] The concept of peripheral crowding (Figure 1, c) is based on the fact that melamines with sterically bulky substituents promote single rosette formation through the introduction of unfavourable steric interactions in the corresponding tape-like structures. [17,21,22] …”

Section: The Ca·m Latticementioning

confidence: 99%

Noncovalent Synthesis of Melamine−Cyanuric/Barbituric Acid Derived Nanostructures: Regio- and Stereoselection

Timmerman

Prins

2001

Eur. J. Org. Chem.

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The hydrogen bond directed self‐assembly of calix[4]arene dimelamines and barbituric or cyanuric acid derivatives gives ready access to organic nanostructures of nanometer dimensions. The synthesis, characterization, and supramolecular chirality of these noncovalent assemblies are discussed in detail, together with means of achieving regio‐, diastereo‐, and enantioselection. Self‐organizing behaviour into higher order aggregates on solid surfaces is also described.

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Section: The Ca·m Latticementioning

confidence: 99%

Noncovalent Synthesis of Melamine−Cyanuric/Barbituric Acid Derived Nanostructures: Regio- and Stereoselection

Timmerman

Prins

2001

Eur. J. Org. Chem.

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“…[2,4,5,6] In this adduct, cyanuric acid and melamine form hydrogen-bonded rosette-like Abstract: Self-assembly of melem C 6 N 7 A C H T U N G T R E N N U N G (NH 2 ) 3 in hot aqueous solution leads to the formation of hydrogenbonded, hexagonal rosettes of melem units surrounding infinite channels with a diameter of 8.9 . The channels are filled with strongly disordered water molecules, which are bound to the melem network through hydrogen bonds.…”

Section: Introductionmentioning

confidence: 99%

“…By employing s-triazine molecules with sterically bulky substituents or allowing preorganization of building units by interconnecting them with a hub linker, the formation of rosettes can be favored over the formation of tapes. [2,5] However, whereas numerous compounds based on the CA·M lattice have been extensively studied by many groups, no comparable structures comprising the analogous but larger s-heptazine (C 6 N 7 ) compounds cyameluric acid or melem (see Scheme 2) are known so far. The molecular structure of the s-heptazine or cyameluric ring system, respectively, has already been postulated by Pauling and Sturdivant in 1937.…”

Section: Introductionmentioning

confidence: 99%

Formation of a Hydrogen‐Bonded Heptazine Framework by Self‐Assembly of Melem into a Hexagonal Channel Structure

Makowski

Köstler

Schnick

2012

Chemistry A European J

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Self-assembly of melem C(6)N(7)(NH(2))(3) in hot aqueous solution leads to the formation of hydrogen-bonded, hexagonal rosettes of melem units surrounding infinite channels with a diameter of 8.9 Å. The channels are filled with strongly disordered water molecules, which are bound to the melem network through hydrogen bonds. Single-crystals of melem hydrate C(6)N(7)(NH(2))(3)⋅xH(2)O (x≈2.3) were obtained by hydrothermal treatment of melem at 200 °C and the crystal structure (R ̅3c, a=2879.0(4), c=664.01(13) pm, V=4766.4(13)×10(6) pm(3), Z=18) was elucidated by single-crystal X-ray diffraction. With respect to the structural similarity to the well-known adduct between melamine and cyanuric acid, the composition of the obtained product was further analyzed by solid-state NMR spectroscopy. Hydrolysis of melem to cyameluric acid during syntheses at elevated temperatures could thus be ruled out. DTA/TG studies revealed that, during heating of melem hydrate, water molecules can be removed from the channels of the structure to a large extent. The solvent-free framework is stable up to 430 °C without transforming into the denser structure of anhydrous melem. Dehydrated melem hydrate was further characterized by solid-state NMR spectroscopy, powder X-ray diffraction, and sorption measurements to investigate structural changes induced by the removal of water from the channels. During dehydration, the hexagonal, layered arrangement of melem units is maintained whereas the formation of additional hydrogen bonds between melem entities requires the stacking mode of hexagonal layers to be altered. It is assumed that layers are shifted perpendicular to the direction of the channels, thereby making them inaccessible for guest molecules.

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“…It was found that barbiturates or cyanurates could self-assemble into highly organized structures such as linear tapes, crinkle tapes, or rosettes with complementary hydrogen-bonding melamines in the solid state or solution. [10][11][12][13][14][15][16][17][18] More recently, the formation of hydrogenbonding networks between these complementary components has also been investigated in 2-D at the air-water interface. 19,20 Traditionally, it was believed that hydrogen bonding directed molecular recognition is difficult in polar media, such as water, due to the competition from the latter.…”

Section: Introductionmentioning

confidence: 99%

Polarization-Modulated Infrared Reflection Absorption Spectroscopic Studies of a Hydrogen-Bonding Network at the Air−Water Interface

et al. 1999

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The hydrogen-bonding network formed between a triaminotriazine amphiphile (2C 18 TAZ, 1) and complementary barbituric acid (BA, 2) at the air-water interface is investigated by polarization-modulated infrared reflection absorption spectroscopy (PM-IRRAS). The molecular structure and orientation of the 1:1 hydrogenbonding network at the air-water interface is revealed in this study. Without the addition of BA to the subphase, the NH 2 scissoring of 2C 18 TAZ appeared in the spectrum as a broad negative absorption band between 1660 and 1605 cm -1 , indicating its perpendicular orientation to the air-water interface. When BA was added to the subphase, the NH 2 scissoring absorption band from the triaminotriazine moiety disappeared due to the complementary hydrogen bonding of BA to the 2C 18 TAZ monolayer. The formation of the rigid 1:1 hydrogen-bonding network also resulted in the disappearance of one of the ring quadrant stretch absorption bands of the 2C 18 TAZ molecule. New bands which are attributed to the vibration of BA can be clearly seen. Particularly, the CdO stretch from BA shows up in the spectra as two negative absorption bands around 1700 cm -1 . The negative signature of these two bands suggests that the BA molecules are oriented in the hydrogen-bonding network with the C-2 carbonyl positioned vertically toward the air, and the C-4 and C-6 carbonyls directed into the water subphase. This is consistent with formation of an assembly which optimizes the use of complementary hydrogen bonding between two components. Furthermore, the effect of competitive polar organic solvents in subphase, such as DMSO, on the hydrogen-bonding network has also been observed in this study. Compared to the previous IRRAS studies on the similar monolayers, the sensitivity of PM-IRRAS is obviously improved. PM-IRRAS will likely become a powerful analytical technique for the characterization of molecular structure and orientation of Langmuir monolayers at the air-water interface.

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Structural Preferences of Hydrogen-Bonded Networks in Organic Solution - the Cyclic CA3.cntdot.M3 "Rosette"

Cited by 191 publications

References 0 publications

Noncovalent Synthesis of Melamine−Cyanuric/Barbituric Acid Derived Nanostructures: Regio- and Stereoselection

Noncovalent Synthesis of Melamine−Cyanuric/Barbituric Acid Derived Nanostructures: Regio- and Stereoselection

Formation of a Hydrogen‐Bonded Heptazine Framework by Self‐Assembly of Melem into a Hexagonal Channel Structure

Polarization-Modulated Infrared Reflection Absorption Spectroscopic Studies of a Hydrogen-Bonding Network at the Air−Water Interface

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