In and , the first author and his collaborators constructed the irreducible symplectic 4-manifolds that are homeomorphic but not diffeomorphic to 74&_mathId=si1.gif&_user=111111111&_pii=S0166864116300074&_rdoc=1&_issn=01668641&md5=5ac813a056ffc0739408cae062643a87">74-si1.gif"> for each integer 74&_mathId=si2.gif&_user=111111111&_pii=S0166864116300074&_rdoc=1&_issn=01668641&md5=0bbd6e24681fa828309375d0e06211c3" title="Click to view the MathML source">n≥25, and the families of simply connected irreducible nonspin symplectic 4-manifolds with positive signature that are interesting with respect to the symplectic geography problem. In this paper, we improve the main results in and . In particular, we construct (i) an infinitely many irreducible symplectic and nonsymplectic 4-manifolds that are homeomorphic but not diffeomorphic to 74&_mathId=si1.gif&_user=111111111&_pii=S0166864116300074&_rdoc=1&_issn=01668641&md5=5ac813a056ffc0739408cae062643a87">74-si1.gif"> for each integer 74&_mathId=si22.gif&_user=111111111&_pii=S0166864116300074&_rdoc=1&_issn=01668641&md5=2bb034860e695ccb5e2913cf5269af48" title="Click to view the MathML source">n≥12, and (ii) the families of simply connected irreducible nonspin symplectic 4-manifolds that have the smallest Euler characteristics among the all known simply connected 4-manifolds with positive signature and with more than one smooth structure. Our construction uses the complex surfaces of Hirzebruch and Bauer–Catanese on Bogomolov–Miyaoka–Yau line with 74&_mathId=si17.gif&_user=111111111&_pii=S0166864116300074&_rdoc=1&_issn=01668641&md5=bc91a13981fd3a0dc7b43776bfd6b9d4">74-si17.gif">, along with the exotic symplectic 4-manifolds constructed in , , , and .