Synergy of Intramolecular Hydrogen-Bonding Network inmyo-Inositol 2-Monophosphate:  Theoretical Investigations into the Electronic Structure, Proton Transfer, and pKa

2005 ◽  
Vol 127 (45) ◽  
pp. 15848-15861 ◽  
Author(s):  
Ping Yang ◽  
Pushpalatha P. N. Murthy ◽  
Richard E. Brown
Keyword(s):  
Hydrogen Bonding ◽  
Electronic Structure ◽  
Proton Transfer ◽  
Intramolecular Hydrogen Bonding ◽  
Theoretical Investigations ◽  
Hydrogen Bonding Network ◽  
Intramolecular Hydrogen

Crystal structures of two polymorphic forms of DOTAM-mono-acid dihydrate

2018 ◽  
Vol 74 (5) ◽  
pp. 542-547
Author(s):  
Paul Jurek ◽  
Garry E. Kiefer ◽  
Frank R. Fronczek
Keyword(s):  
Hydrogen Bonding ◽  
Intramolecular Hydrogen Bonding ◽  
Temperature Structure ◽  
Intermolecular Hydrogen Bonding ◽  
Space Group ◽  
Pendant Arm ◽  
Polymorphic Forms ◽  
Higher Temperature ◽  
Hydrogen Bonding Network ◽  
Intramolecular Hydrogen

The structural chemistry of 2-[4,7,10-tris(carbamoylmethyl)-1,4,7,10-tetraazacyclododecan-1-yl]acetic acid dihydrate, C16H31N7O5·2H2O, is described. The macrocyclic compound, also known by the abbreviation DOTAM-mono-acid, crystallized at room temperature and was isolated concomitantly as two polymorphic forms. The structures of both polymorphs were determined at 90 K. The first polymorph crystallized as a zwitterionic dihydrate [systematic name: 4,7,10-tris(carbamoylmethyl)-1-(carboxylatomethyl)-1,4,7,10-tetraazacyclododecan-1-ium dihydrate] in the space group P21/n, with Z′ = 1. The second polymorph crystallized as a zwitterionic dihydrate in the space group P21 at 90 K, with Z′ = 2. The two independent molecules are related by a local center. In each polymorph, the zwitterion is formed between the negatively-charged carboxylate group and the ring N atom that bears the acetate pendant arm. Extensive inter- and intramolecular hydrogen bonding exists in both polymorphic structures. In polymorph 1, an intermolecular hydrogen-bonding network propagating parallel to the a direction creates an infinite chain. A second hydrogen-bonding network is observed through a water molecule of hydration in the b direction. Polymorph 2 also has two intermolecular hydrogen-bonding networks. One propagates parallel to the a direction, while the other propagates in the [\overline{1}10] direction. Increasing the temperature of polymorph 2 yields the same structure at T = 180 K, but the pseudocenter becomes exact at 299 K. The higher-temperature structure has Z′ = 1 in the space group P21/c.

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