3,7-bis(2,6-dimethylphenyl)-2,8-dimethyl-11-(trifluoromethyl)-3,7,13-triazoniatricyclo[7.3.1.05,13]trideca-1(12),2,7,9(13),10-pentaene;3,7-bis(2,6-dimethylphenyl)-2,8,11-trimethyl-3,7,13-triazoniatricyclo[7.3.1.05,13]trideca-1(12),2,7,9(13),10-pentaene;10,18-dimethyl-3,25-diaza-10,18,27-triazoniaheptacyclo[14.10.1.03,11.04,9.012,27.017,25.019,24]heptacosa-4,6,8,10,12(27),13,15,17,19,21,23-undecaene;10,18-dithia-3,25,27-triazoniaheptacyclo[14.10.1.03,11.04,9.012,27.017,25.019,24]heptacosa-3(11),4,6,8,12(27),13,15,17(25),19,21,23-undecaene;3,19,21-triazoniapentacyclo[11.7.1.03,8.09,21.014,19]henicosa-3,5,7,9(21),10,12,14,16,18-nonaene;2,8,11-trimethyl-3,7-bis(2,4,6-trimethylphenyl)-3,7,13-triazoniatricyclo[7.3.1.05,13]trideca-1(12),2,7,9(13),10-pentaene

C153H157F3N20S2+18 — CID 159537615

About 3,7-bis(2,6-dimethylphenyl)-2,8-dimethyl-11-(trifluoromethyl)-3,7,13-triazoniatricyclo[7.3.1.05,13]trideca-1(12),2,7,9(13),10-pentaene;3,7-bis(2,6-dimethylphenyl)-2,8,11-trimethyl-3,7,13-triazoniatricyclo[7.3.1.05,13]trideca-1(12),2,7,9(13),10-pentaene;10,18-dimethyl-3,25-diaza-10,18,27-triazoniaheptacyclo[14.10.1.03,11.04,9.012,27.017,25.019,24]heptacosa-4,6,8,10,12(27),13,15,17,19,21,23-undecaene;10,18-dithia-3,25,27-triazoniaheptacyclo[14.10.1.03,11.04,9.012,27.017,25.019,24]heptacosa-3(11),4,6,8,12(27),13,15,17(25),19,21,23-undecaene;3,19,21-triazoniapentacyclo[11.7.1.03,8.09,21.014,19]henicosa-3,5,7,9(21),10,12,14,16,18-nonaene;2,8,11-trimethyl-3,7-bis(2,4,6-trimethylphenyl)-3,7,13-triazoniatricyclo[7.3.1.05,13]trideca-1(12),2,7,9(13),10-pentaene

3,7-bis(2,6-dimethylphenyl)-2,8-dimethyl-11-(trifluoromethyl)-3,7,13-triazoniatricyclo[7.3.1.05,13]trideca-1(12),2,7,9(13),10-pentaene;3,7-bis(2,6-dimethylphenyl)-2,8,11-trimethyl-3,7,13-triazoniatricyclo[7.3.1.05,13]trideca-1(12),2,7,9(13),10-pentaene;10,18-dimethyl-3,25-diaza-10,18,27-triazoniaheptacyclo[14.10.1.03,11.04,9.012,27.017,25.019,24]heptacosa-4,6,8,10,12(27),13,15,17,19,21,23-undecaene;10,18-dithia-3,25,27-triazoniaheptacyclo[14.10.1.03,11.04,9.012,27.017,25.019,24]heptacosa-3(11),4,6,8,12(27),13,15,17(25),19,21,23-undecaene;3,19,21-triazoniapentacyclo[11.7.1.03,8.09,21.014,19]henicosa-3,5,7,9(21),10,12,14,16,18-nonaene;2,8,11-trimethyl-3,7-bis(2,4,6-trimethylphenyl)-3,7,13-triazoniatricyclo[7.3.1.05,13]trideca-1(12),2,7,9(13),10-pentaene (PubChem CID 159537615) has the molecular formula C153H157F3N20S2+18 and a molecular weight of 2397.21 g/mol. Its IUPAC name is 3,7-bis(2,6-dimethylphenyl)-2,8-dimethyl-11-(trifluoromethyl)-3,7,13-triazoniatricyclo[7.3.1.05,13]trideca-1(12),2,7,9(13),10-pentaene;3,7-bis(2,6-dimethylphenyl)-2,8,11-trimethyl-3,7,13-triazoniatricyclo[7.3.1.05,13]trideca-1(12),2,7,9(13),10-pentaene;10,18-dimethyl-3,25-diaza-10,18,27-triazoniaheptacyclo[14.10.1.03,11.04,9.012,27.017,25.019,24]heptacosa-4,6,8,10,12(27),13,15,17,19,21,23-undecaene;10,18-dithia-3,25,27-triazoniaheptacyclo[14.10.1.03,11.04,9.012,27.017,25.019,24]heptacosa-3(11),4,6,8,12(27),13,15,17(25),19,21,23-undecaene;3,19,21-triazoniapentacyclo[11.7.1.03,8.09,21.014,19]henicosa-3,5,7,9(21),10,12,14,16,18-nonaene;2,8,11-trimethyl-3,7-bis(2,4,6-trimethylphenyl)-3,7,13-triazoniatricyclo[7.3.1.05,13]trideca-1(12),2,7,9(13),10-pentaene.

Molecular Properties

• Compound Name: 3,7-bis(2,6-dimethylphenyl)-2,8-dimethyl-11-(trifluoromethyl)-3,7,13-triazoniatricyclo[7.3.1.05,13]trideca-1(12),2,7,9(13),10-pentaene;3,7-bis(2,6-dimethylphenyl)-2,8,11-trimethyl-3,7,13-triazoniatricyclo[7.3.1.05,13]trideca-1(12),2,7,9(13),10-pentaene;10,18-dimethyl-3,25-diaza-10,18,27-triazoniaheptacyclo[14.10.1.03,11.04,9.012,27.017,25.019,24]heptacosa-4,6,8,10,12(27),13,15,17,19,21,23-undecaene;10,18-dithia-3,25,27-triazoniaheptacyclo[14.10.1.03,11.04,9.012,27.017,25.019,24]heptacosa-3(11),4,6,8,12(27),13,15,17(25),19,21,23-undecaene;3,19,21-triazoniapentacyclo[11.7.1.03,8.09,21.014,19]henicosa-3,5,7,9(21),10,12,14,16,18-nonaene;2,8,11-trimethyl-3,7-bis(2,4,6-trimethylphenyl)-3,7,13-triazoniatricyclo[7.3.1.05,13]trideca-1(12),2,7,9(13),10-pentaene
• PubChem CID: 159537615
• Molecular Formula: C153H157F3N20S2+18
• Molecular Weight: 2397.21 g/mol
• Exact Mass: 2395.22
• IUPAC Name: 3,7-bis(2,6-dimethylphenyl)-2,8-dimethyl-11-(trifluoromethyl)-3,7,13-triazoniatricyclo[7.3.1.05,13]trideca-1(12),2,7,9(13),10-pentaene;3,7-bis(2,6-dimethylphenyl)-2,8,11-trimethyl-3,7,13-triazoniatricyclo[7.3.1.05,13]trideca-1(12),2,7,9(13),10-pentaene;10,18-dimethyl-3,25-diaza-10,18,27-triazoniaheptacyclo[14.10.1.03,11.04,9.012,27.017,25.019,24]heptacosa-4,6,8,10,12(27),13,15,17,19,21,23-undecaene;10,18-dithia-3,25,27-triazoniaheptacyclo[14.10.1.03,11.04,9.012,27.017,25.019,24]heptacosa-3(11),4,6,8,12(27),13,15,17(25),19,21,23-undecaene;3,19,21-triazoniapentacyclo[11.7.1.03,8.09,21.014,19]henicosa-3,5,7,9(21),10,12,14,16,18-nonaene;2,8,11-trimethyl-3,7-bis(2,4,6-trimethylphenyl)-3,7,13-triazoniatricyclo[7.3.1.05,13]trideca-1(12),2,7,9(13),10-pentaene
• SMILES: CC1=[N+](c2c(C)cc(C)cc2C)CC2C[N+](c3c(C)cc(C)cc3C)=C(C)c3cc(C)cc1[n+]32.CC1=[N+](c2c(C)cccc2C)CC2C[N+](c3c(C)cccc3C)=C(C)c3cc(C(F)(F)F)cc1[n+]32.CC1=[N+](c2c(C)cccc2C)CC2C[N+](c3c(C)cccc3C)=C(C)c3cc(C)cc1[n+]32.C[n+]1c2n(c3ccccc31)CC1Cn3c([n+](C)c4ccccc43)-c3cccc-2[n+]31.c1cc2[n+]3c(c1)-c1sc4ccccc4[n+]1CC3C[n+]1c-2sc2ccccc21.c1cc[n+]2c(c1)-c1cccc3[n+]1C(C2)C[n+]1ccccc1-3
• InChI: InChI=1S/C31H38N3.C29H31F3N3.C29H34N3.C24H22N5.C22H16N3S2.C18H16N3/c1-18-10-21(4)30(22(5)11-18)32-16-27-17-33(31-23(6)12-19(2)13-24(31)7)26(9)29-15-20(3)14-28(25(32)8)34(27)29;1-17-9-7-10-18(2)27(17)33-15-24-16-34(28-19(3)11-8-12-20(28)4)22(6)26-14-23(29(30,31)32)13-25(21(33)5)35(24)26;1-18-14-26-23(6)30(28-19(2)10-8-11-20(28)3)16-25-17-31(24(7)27(15-18)32(25)26)29-21(4)12-9-13-22(29)5;1-25-17-8-3-5-10-19(17)27-14-16-15-28-20-11-6-4-9-18(20)26(2)24(28)22-13-7-12-21(23(25)27)29(16)22;1-3-10-19-15(6-1)23-12-14-13-24-16-7-2-4-11-20(16)27-22(24)18-9-5-8-17(25(14)18)21(23)26-19;1-3-10-19-12-14-13-20-11-4-2-7-16(20)18-9-5-8-17(21(14)18)15(19)6-1/h10-15,27H,16-17H2,1-9H3;7-14,24H,15-16H2,1-6H3;8-15,25H,16-17H2,1-7H3;3-13,16H,14-15H2,1-2H3;1-11,14H,12-13H2;1-11,14H,12-13H2/q6*+3
• InChIKey: CZLGNNCFHDTNKK-UHFFFAOYSA-N
• XLogP: 25.27
• TPSA: 74.48 Ų
• H-Bond Acceptors: 4
• Rotatable Bonds: 6
• Heavy Atoms: 178
• Complexity: —

Lipinski Rule of Five

2 violations

Rule	Value
MW ≤ 500	2397.21
LogP ≤ 5	25.27
H-Bond Donors ≤ 5	0
H-Bond Acceptors ≤ 10	4

Computed Properties (RDKit)

• Structural Alerts: {'alert_name': 'quaternary_nitrogen_1', 'substructure': 'N/A'}

Frequently Asked Questions

What is the IUPAC name of 3,7-bis(2,6-dimethylphenyl)-2,8-dimethyl-11-(trifluoromethyl)-3,7,13-triazoniatricyclo[7.3.1.05,13]trideca-1(12),2,7,9(13),10-pentaene;3,7-bis(2,6-dimethylphenyl)-2,8,11-trimethyl-3,7,13-triazoniatricyclo[7.3.1.05,13]trideca-1(12),2,7,9(13),10-pentaene;10,18-dimethyl-3,25-diaza-10,18,27-triazoniaheptacyclo[14.10.1.03,11.04,9.012,27.017,25.019,24]heptacosa-4,6,8,10,12(27),13,15,17,19,21,23-undecaene;10,18-dithia-3,25,27-triazoniaheptacyclo[14.10.1.03,11.04,9.012,27.017,25.019,24]heptacosa-3(11),4,6,8,12(27),13,15,17(25),19,21,23-undecaene;3,19,21-triazoniapentacyclo[11.7.1.03,8.09,21.014,19]henicosa-3,5,7,9(21),10,12,14,16,18-nonaene;2,8,11-trimethyl-3,7-bis(2,4,6-trimethylphenyl)-3,7,13-triazoniatricyclo[7.3.1.05,13]trideca-1(12),2,7,9(13),10-pentaene?

The IUPAC name of 3,7-bis(2,6-dimethylphenyl)-2,8-dimethyl-11-(trifluoromethyl)-3,7,13-triazoniatricyclo[7.3.1.05,13]trideca-1(12),2,7,9(13),10-pentaene;3,7-bis(2,6-dimethylphenyl)-2,8,11-trimethyl-3,7,13-triazoniatricyclo[7.3.1.05,13]trideca-1(12),2,7,9(13),10-pentaene;10,18-dimethyl-3,25-diaza-10,18,27-triazoniaheptacyclo[14.10.1.03,11.04,9.012,27.017,25.019,24]heptacosa-4,6,8,10,12(27),13,15,17,19,21,23-undecaene;10,18-dithia-3,25,27-triazoniaheptacyclo[14.10.1.03,11.04,9.012,27.017,25.019,24]heptacosa-3(11),4,6,8,12(27),13,15,17(25),19,21,23-undecaene;3,19,21-triazoniapentacyclo[11.7.1.03,8.09,21.014,19]henicosa-3,5,7,9(21),10,12,14,16,18-nonaene;2,8,11-trimethyl-3,7-bis(2,4,6-trimethylphenyl)-3,7,13-triazoniatricyclo[7.3.1.05,13]trideca-1(12),2,7,9(13),10-pentaene (CID 159537615) is 3,7-bis(2,6-dimethylphenyl)-2,8-dimethyl-11-(trifluoromethyl)-3,7,13-triazoniatricyclo[7.3.1.05,13]trideca-1(12),2,7,9(13),10-pentaene;3,7-bis(2,6-dimethylphenyl)-2,8,11-trimethyl-3,7,13-triazoniatricyclo[7.3.1.05,13]trideca-1(12),2,7,9(13),10-pentaene;10,18-dimethyl-3,25-diaza-10,18,27-triazoniaheptacyclo[14.10.1.03,11.04,9.012,27.017,25.019,24]heptacosa-4,6,8,10,12(27),13,15,17,19,21,23-undecaene;10,18-dithia-3,25,27-triazoniaheptacyclo[14.10.1.03,11.04,9.012,27.017,25.019,24]heptacosa-3(11),4,6,8,12(27),13,15,17(25),19,21,23-undecaene;3,19,21-triazoniapentacyclo[11.7.1.03,8.09,21.014,19]henicosa-3,5,7,9(21),10,12,14,16,18-nonaene;2,8,11-trimethyl-3,7-bis(2,4,6-trimethylphenyl)-3,7,13-triazoniatricyclo[7.3.1.05,13]trideca-1(12),2,7,9(13),10-pentaene.

What is the SMILES notation for 3,7-bis(2,6-dimethylphenyl)-2,8-dimethyl-11-(trifluoromethyl)-3,7,13-triazoniatricyclo[7.3.1.05,13]trideca-1(12),2,7,9(13),10-pentaene;3,7-bis(2,6-dimethylphenyl)-2,8,11-trimethyl-3,7,13-triazoniatricyclo[7.3.1.05,13]trideca-1(12),2,7,9(13),10-pentaene;10,18-dimethyl-3,25-diaza-10,18,27-triazoniaheptacyclo[14.10.1.03,11.04,9.012,27.017,25.019,24]heptacosa-4,6,8,10,12(27),13,15,17,19,21,23-undecaene;10,18-dithia-3,25,27-triazoniaheptacyclo[14.10.1.03,11.04,9.012,27.017,25.019,24]heptacosa-3(11),4,6,8,12(27),13,15,17(25),19,21,23-undecaene;3,19,21-triazoniapentacyclo[11.7.1.03,8.09,21.014,19]henicosa-3,5,7,9(21),10,12,14,16,18-nonaene;2,8,11-trimethyl-3,7-bis(2,4,6-trimethylphenyl)-3,7,13-triazoniatricyclo[7.3.1.05,13]trideca-1(12),2,7,9(13),10-pentaene?

The canonical SMILES for 3,7-bis(2,6-dimethylphenyl)-2,8-dimethyl-11-(trifluoromethyl)-3,7,13-triazoniatricyclo[7.3.1.05,13]trideca-1(12),2,7,9(13),10-pentaene;3,7-bis(2,6-dimethylphenyl)-2,8,11-trimethyl-3,7,13-triazoniatricyclo[7.3.1.05,13]trideca-1(12),2,7,9(13),10-pentaene;10,18-dimethyl-3,25-diaza-10,18,27-triazoniaheptacyclo[14.10.1.03,11.04,9.012,27.017,25.019,24]heptacosa-4,6,8,10,12(27),13,15,17,19,21,23-undecaene;10,18-dithia-3,25,27-triazoniaheptacyclo[14.10.1.03,11.04,9.012,27.017,25.019,24]heptacosa-3(11),4,6,8,12(27),13,15,17(25),19,21,23-undecaene;3,19,21-triazoniapentacyclo[11.7.1.03,8.09,21.014,19]henicosa-3,5,7,9(21),10,12,14,16,18-nonaene;2,8,11-trimethyl-3,7-bis(2,4,6-trimethylphenyl)-3,7,13-triazoniatricyclo[7.3.1.05,13]trideca-1(12),2,7,9(13),10-pentaene is CC1=[N+](c2c(C)cc(C)cc2C)CC2C[N+](c3c(C)cc(C)cc3C)=C(C)c3cc(C)cc1[n+]32.CC1=[N+](c2c(C)cccc2C)CC2C[N+](c3c(C)cccc3C)=C(C)c3cc(C(F)(F)F)cc1[n+]32.CC1=[N+](c2c(C)cccc2C)CC2C[N+](c3c(C)cccc3C)=C(C)c3cc(C)cc1[n+]32.C[n+]1c2n(c3ccccc31)CC1Cn3c([n+](C)c4ccccc43)-c3cccc-2[n+]31.c1cc2[n+]3c(c1)-c1sc4ccccc4[n+]1CC3C[n+]1c-2sc2ccccc21.c1cc[n+]2c(c1)-c1cccc3[n+]1C(C2)C[n+]1ccccc1-3.

What is the InChIKey of 3,7-bis(2,6-dimethylphenyl)-2,8-dimethyl-11-(trifluoromethyl)-3,7,13-triazoniatricyclo[7.3.1.05,13]trideca-1(12),2,7,9(13),10-pentaene;3,7-bis(2,6-dimethylphenyl)-2,8,11-trimethyl-3,7,13-triazoniatricyclo[7.3.1.05,13]trideca-1(12),2,7,9(13),10-pentaene;10,18-dimethyl-3,25-diaza-10,18,27-triazoniaheptacyclo[14.10.1.03,11.04,9.012,27.017,25.019,24]heptacosa-4,6,8,10,12(27),13,15,17,19,21,23-undecaene;10,18-dithia-3,25,27-triazoniaheptacyclo[14.10.1.03,11.04,9.012,27.017,25.019,24]heptacosa-3(11),4,6,8,12(27),13,15,17(25),19,21,23-undecaene;3,19,21-triazoniapentacyclo[11.7.1.03,8.09,21.014,19]henicosa-3,5,7,9(21),10,12,14,16,18-nonaene;2,8,11-trimethyl-3,7-bis(2,4,6-trimethylphenyl)-3,7,13-triazoniatricyclo[7.3.1.05,13]trideca-1(12),2,7,9(13),10-pentaene?

The InChIKey is CZLGNNCFHDTNKK-UHFFFAOYSA-N. The full InChI is InChI=1S/C31H38N3.C29H31F3N3.C29H34N3.C24H22N5.C22H16N3S2.C18H16N3/c1-18-10-21(4)30(22(5)11-18)32-16-27-17-33(31-23(6)12-19(2)13-24(31)7)26(9)29-15-20(3)14-28(25(32)8)34(27)29;1-17-9-7-10-18(2)27(17)33-15-24-16-34(28-19(3)11-8-12-20(28)4)22(6)26-14-23(29(30,31)32)13-25(21(33)5)35(24)26;1-18-14-26-23(6)30(28-19(2)10-8-11-20(28)3)16-25-17-31(24(7)27(15-18)32(25)26)29-21(4)12-9-13-22(29)5;1-25-17-8-3-5-10-19(17)27-14-16-15-28-20-11-6-4-9-18(20)26(2)24(28)22-13-7-12-21(23(25)27)29(16)22;1-3-10-19-15(6-1)23-12-14-13-24-16-7-2-4-11-20(16)27-22(24)18-9-5-8-17(25(14)18)21(23)26-19;1-3-10-19-12-14-13-20-11-4-2-7-16(20)18-9-5-8-17(21(14)18)15(19)6-1/h10-15,27H,16-17H2,1-9H3;7-14,24H,15-16H2,1-6H3;8-15,25H,16-17H2,1-7H3;3-13,16H,14-15H2,1-2H3;1-11,14H,12-13H2;1-11,14H,12-13H2/q6*+3.

What are the key properties of 3,7-bis(2,6-dimethylphenyl)-2,8-dimethyl-11-(trifluoromethyl)-3,7,13-triazoniatricyclo[7.3.1.05,13]trideca-1(12),2,7,9(13),10-pentaene;3,7-bis(2,6-dimethylphenyl)-2,8,11-trimethyl-3,7,13-triazoniatricyclo[7.3.1.05,13]trideca-1(12),2,7,9(13),10-pentaene;10,18-dimethyl-3,25-diaza-10,18,27-triazoniaheptacyclo[14.10.1.03,11.04,9.012,27.017,25.019,24]heptacosa-4,6,8,10,12(27),13,15,17,19,21,23-undecaene;10,18-dithia-3,25,27-triazoniaheptacyclo[14.10.1.03,11.04,9.012,27.017,25.019,24]heptacosa-3(11),4,6,8,12(27),13,15,17(25),19,21,23-undecaene;3,19,21-triazoniapentacyclo[11.7.1.03,8.09,21.014,19]henicosa-3,5,7,9(21),10,12,14,16,18-nonaene;2,8,11-trimethyl-3,7-bis(2,4,6-trimethylphenyl)-3,7,13-triazoniatricyclo[7.3.1.05,13]trideca-1(12),2,7,9(13),10-pentaene?

3,7-bis(2,6-dimethylphenyl)-2,8-dimethyl-11-(trifluoromethyl)-3,7,13-triazoniatricyclo[7.3.1.05,13]trideca-1(12),2,7,9(13),10-pentaene;3,7-bis(2,6-dimethylphenyl)-2,8,11-trimethyl-3,7,13-triazoniatricyclo[7.3.1.05,13]trideca-1(12),2,7,9(13),10-pentaene;10,18-dimethyl-3,25-diaza-10,18,27-triazoniaheptacyclo[14.10.1.03,11.04,9.012,27.017,25.019,24]heptacosa-4,6,8,10,12(27),13,15,17,19,21,23-undecaene;10,18-dithia-3,25,27-triazoniaheptacyclo[14.10.1.03,11.04,9.012,27.017,25.019,24]heptacosa-3(11),4,6,8,12(27),13,15,17(25),19,21,23-undecaene;3,19,21-triazoniapentacyclo[11.7.1.03,8.09,21.014,19]henicosa-3,5,7,9(21),10,12,14,16,18-nonaene;2,8,11-trimethyl-3,7-bis(2,4,6-trimethylphenyl)-3,7,13-triazoniatricyclo[7.3.1.05,13]trideca-1(12),2,7,9(13),10-pentaene has a molecular weight of 2397.21 g/mol, XLogP of 25.27, 6 rotatable bonds, 0 hydrogen bond donors, and 4 hydrogen bond acceptors.

Where does this data come from?

All data for 3,7-bis(2,6-dimethylphenyl)-2,8-dimethyl-11-(trifluoromethyl)-3,7,13-triazoniatricyclo[7.3.1.05,13]trideca-1(12),2,7,9(13),10-pentaene;3,7-bis(2,6-dimethylphenyl)-2,8,11-trimethyl-3,7,13-triazoniatricyclo[7.3.1.05,13]trideca-1(12),2,7,9(13),10-pentaene;10,18-dimethyl-3,25-diaza-10,18,27-triazoniaheptacyclo[14.10.1.03,11.04,9.012,27.017,25.019,24]heptacosa-4,6,8,10,12(27),13,15,17,19,21,23-undecaene;10,18-dithia-3,25,27-triazoniaheptacyclo[14.10.1.03,11.04,9.012,27.017,25.019,24]heptacosa-3(11),4,6,8,12(27),13,15,17(25),19,21,23-undecaene;3,19,21-triazoniapentacyclo[11.7.1.03,8.09,21.014,19]henicosa-3,5,7,9(21),10,12,14,16,18-nonaene;2,8,11-trimethyl-3,7-bis(2,4,6-trimethylphenyl)-3,7,13-triazoniatricyclo[7.3.1.05,13]trideca-1(12),2,7,9(13),10-pentaene is sourced from PubChem (CID 159537615), the world's largest open chemistry database maintained by the National Library of Medicine (NIH).