A compound of formula I: or a pharmaceutically acceptable salt thereof, wherein: R 1 is selected from the list of structures consisting of each of R 2, R 3, R 4, R 5, R 6 and R 7 is independently selected from the group consisting of hydrogen, halogen, -CN, -CF 3, -OR, -NR 2, -NO 2, -COOR, -CONR 2, and -R; R 8 is selected from the group consisting of 4-7 membered optionally substituted saturated heterocyclic ring having 1-2 heteroatoms independently selected from nitrogen, oxygen or sulfur, and 5-6 membered heteroaromatic ring having 1-2 heteroatoms independently selected from sulfur, nitrogen and oxygen; R 9 is selected from the group consisting of hydrogen, L-R 13, NH 2, guanidino, 4-7 membered optionally substituted saturated heterocyclic ring having 1-2 heteroatoms independently selected from nitrogen, oxygen and sulfur, and 5-6 membered heteroaromatic ring having 1-2 heteroatoms independently selected from sulfur, nitrogen and oxygen; wherein, when one R 9 group is present, R 9 cannot be hydrogen and when two R 9 groups are present, one must be hydrogen and the other must not be hydrogen; each R 10 is independently selected from the group consisting of hydrogen, halogen, -CN, -CF 3, -OR, -NR 2, -NO 2, -COOR, -CONR 2, and -R; R 11 is hydrogen, NH 2, 4-7 membered optionally substituted saturated heterocyclic ring having 1-2 heteroatoms independently selected from nitrogen, oxygen and sulfur, and 5-6 membered heteroaromatic ring having 1-2 heteroatoms independently selected from sulfur, nitrogen and oxygen; R 12 is hydrogen or optionally substituted C 1-6 aliphatic; L is a covalent bond or a straight or branched C 1-6 aliphatic group, wherein one or more methylene groups are independently and optionally replaced by -NR 14 - or -O-; R 13 is selected from the group consisting of NH 2, guanidino, 4-7 membered optionally substituted saturated heterocyclic ring having 1-2 heteroatoms independently selected from nitrogen, oxygen or sulfur, and 5-6 membered heteroaromatic ring having 1-2 heteroatoms independently selected from sulfur, nitrogen and oxygen; each R 14 is independently hydrogen or C 1-3 aliphatic; and each R is independently hydrogen or optionally substituted C 1-6 aliphatic. each of R 2, R 3, R 4, R 5, R 6 and R 7 is independently selected from the group consisting of hydrogen, halogen, -CN, -CF 3, -OR, -NR 2, -NO 2, -COOR, -CONR 2, and -R; R 8 is selected from the group consisting of 4-7 membered optionally substituted saturated heterocyclic ring having 1-2 heteroatoms independently selected from nitrogen, oxygen or sulfur, and 5-6 membered heteroaromatic ring having 1-2 heteroatoms independently selected from sulfur, nitrogen and oxygen; R 9 is selected from the group consisting of hydrogen, L-R 13, NH 2, guanidino, 4-7 membered optionally substituted saturated heterocyclic ring having 1-2 heteroatoms independently selected from nitrogen, oxygen and sulfur, and 5-6 membered heteroaromatic ring having 1-2 heteroatoms independently selected from sulfur, nitrogen and oxygen; wherein, when one R 9 group is present, R 9 cannot be hydrogen and when two R 9 groups are present, one must be hydrogen and the other must not be hydrogen; each R 10 is independently selected from the group consisting of hydrogen, halogen, -CN, -CF 3, -OR, -NR 2, -NO 2, -COOR, -CONR 2, and -R; R 11 is hydrogen, NH 2, 4-7 membered optionally substituted saturated heterocyclic ring having 1-2 heteroatoms independently selected from nitrogen, oxygen and sulfur, and 5-6 membered heteroaromatic ring having 1-2 heteroatoms independently selected from sulfur, nitrogen and oxygen; R 12 is hydrogen or optionally substituted C 1-6 aliphatic; L is a covalent bond or a straight or branched C 1-6 aliphatic group, wherein one or more methylene groups are independently and optionally replaced by -NR 14 - or -O-; R 13 is selected from the group consisting of NH 2, guanidino, 4-7 membered optionally substituted saturated heterocyclic ring having 1-2 heteroatoms independently selected from nitrogen, oxygen or sulfur, and 5-6 membered heteroaromatic ring having 1-2 heteroatoms independently selected from sulfur, nitrogen and oxygen; each R 14 is independently hydrogen or C 1-3 aliphatic; and each R is independently hydrogen or optionally substituted C 1-6 aliphatic.