Synthesis and Structural Characterization of N,N-disubstituted Acylguanidines

A series of five N,N-disubstituted acylguanidines R~1C(O)N=C[N(H)R~2]NR_2~3(R~1=Mes or Ph; R~2=Ar??or Ar?; R~3=Cy, Bn, iPr, or Et)(Mes=2,4,6-Me_3C_6H_2, Ar??=2,6-iPr_2C_6H_3, Ar?=2,6-Me_2C_6H_3) was synthesized from the reactions of parent acylthioureas with respective secondary amines. According to structutral characterization by single-crystal X-ray diffraction, the rough reduction of the steric hindrance of R substitutents of R~1 C(O)N=C[N(H)R~2]NR_2~3(also abbreviated as R~1-R~2-R~3 for comparison purposes) led to the slight enlongation of N(1)–C(1) bond lengthes and small decrease of N(1)–C(1)–N(3) bond angles from Mes–Ar??–Cy(1) to Ph–Ar??–Bn(2), Ph–Ar??–iPr(3) and Ph–Ar?–Cy(4). At the same time, the N(1)–H(1)···O(1) intramolecular hydrogen bonds were observed in these cases. When R~3=Et, an interesting compound Ph-Ar?-Et(5) was obtained with the formation of intermolecular hydrogen bonds instead. 1 belongs to the monoclinic system, space group P2_(1/n) with a=9.6488(3), b=28.5318(8), c=11.9155(3) ?, b=91.439(2)o, V=3279.27(16) ?~3, and Z=4. 2 belongs to the triclinic system, space group P1 with a=9.6759(7), b=10.8613(8), c=15.7642(12) ?, a=70.429(3), b=79.257(4), g=69.052(4)o, V=1453.63(19) ?~3 and Z=2. 3 belongs to the monoclinic system, space group P2_(1/c) with a=11.1393(4), b=13.0643(4), c=17.6600(6) ?, b=101.866(2)o, V=2515.09(15) ?~3 and Z=4. 4 belongs to the monoclinic system, space group C2/c with a=17.8466(3), b=13.6126(2), c=21.6710(4) ?, b=90.7310(10)o, V=4992.72(14) ?~3 and Z=8. 5 is of orthorhombic system, space group P2_12_12_1 with a=10.5555(2), b=11.8913(2), c=14.9558(4) ?, V=1877.23(5) ?~3 and Z=4.     

Synthesis and Characterization of Aryl Acylguanidines and Their Copper(Ⅱ) Complexes

A series of eight N-mono-substituted aryl acylguanidines L~(1～8) were synthesized from the reactions of their parent acylthioureas and respective primary amines, including five R~1C(O)N=C(NHR~2)_2 with balanced arms(denoted as R~1–R~2–R~2: Ph–Ar'–Ar', L~1(1); Ph–Ar'–Ar', L~2(2); 1-Naph–Ar'–Ar', L~3(3); 1-Naph–Ar'–Ar', L~4(4); 2-Naph–Ar'–Ar', L`5(5); Ar' = 2,6-Me_2C_6H_3, Ar' = 2,6-iPr_2C_6H_3) and three R~1C(O)N=C(NHR~2)NHR~3 with unbalanced arms(denoted as R~1–R~2–R~3: Ph–Ar'–Ph, L~6(6); Ph–Ar' –Ph, L~7(7); Ph–Ar' –Ar', L~8(8)). Treatment of L~(1～5)(1～5) with copper acetate in a molar ratio of 2:1 in dichloromethane led to the formation of homoleptic Cu(Ⅱ) complexes trans-L_2~(n')Cu(9～13), in which the Cu(Ⅱ) center was stabilized by deprotonated ligands Ln'(n = 1～5) in the O,N-bidentate mode. When similar reactions of L~6(Ph–Ar'–Ph)(6) and L~7(Ph–Ar'–Ph)(7) that contain unbalanced arms were investigated, the Cu(Ⅱ) products trans-L_2~(6')Cu(14) and trans-L_2~(7')Cu(15) were formed by deprotonating the bulky amine groups in Ln(-NHAr' for L~6 and-NHAr' for L~7) rather than the-NHPh group. In sharp contrast, trans-L_2~(8')Cu(16) was obtained from two-arm unbalanced L~8(Ph–Ar'–Ar')(8) not by deprotonating the more bulky-NHAr' group but the relatively less bulky-NHAr' group. In a further exploration, the reaction of 1:1 mixed ligands Ln and Lm with copper acetate was found to give only homoleptic Cu(Ⅱ) complex L_2~(n')Cu instead of the heteroleptic one L~(n')CuL~(m'). The in vitro antibacterial activity of L~n was evaluated against S. aureus, E. coli and C. albicans by determining the minimum inhibitory concentrations(MICs) using Kirby-Bauer test.