As　one　of　the　most　investigated　organic　compounds,　phthalocyanines　(Pcs)　exhibit　a　stronger　optical　limiting　response　that　can　be　used　to　protect　human　eyes,　optical　elements,　and　sensors　from　intense　laser　pulses,　however,　they　tend　to　aggregate　at　high　concentration.　This　aggregation　usually　adds　relaxation　pathways,　shorten　the　excited　state　lifetime,　and　reduce　the　effective　nonlinear　absorption.　A　best　strategy　for　reducing　the　intermolecular　interactions　between　Pc　molecules　is　to　introduce　more　or　less　bulky　axial　substituents　with　which　it　would　be　expected　to　alter　the　electronic　structure　of　the　Pc　compounds,　to　introduce　a　dipole　moment　perpendicular　to　the　macrocycle,　and　to　alter　both　intermolecular　interactions　as　well　as　spatial　relationships　between　neighboring　molecules.　As　a　result,　a　whole　series　of　new　highly　soluble　axially　substituted　MPc　(M=　In,　Ga,　Ti)　compounds　have　been　synthesized　by　us　in　recent　years.　Of　interest　is　that　their　limiting　response　can　be　tailored　over　a　very　broad　range　due　to　the　high　architectural　flexibility　of　the　Pc　structure.　Future　work　will　be　focused　on　in-depth　studies　of　the　Pc-based　solution　and　solid　state　systems　to　provide　a　detailed　understanding　of　the　factors　affecting　the　optical　limiting　response.　©　2009　Bentham　Science　Publishers　Ltd.