Hello, Velayutham,

as a rule, using vacuum is quite a mild method of drying materials. If the genuine structure remains stable without water or another liquid medium, which means no framework collapse occured during drying or removal, respectively, there won't be any changes in MOF's surface area. But have in mind that measured "surface area" values of undried and dried MO frameworks differ from each other. That's because liquid would occupy intra-framework space and prevent uptake of sorbing probe molecules used to determine specific surface area.

It should not have a negative effect. It can only free-up surface if you have something adsorbed (ambient gas or moisture or something else) on its surface. Therefore, in order to gain more accurate measurement, vacuum drying is recommended.

This is a complex question. Vacuum drying is probably the least evasive technique and also it is the first thought that comes to mind when evacuating a material. Non the less even vaccum drying may have a detrimental effect on the material. It all has to do with the material you are evacuating. Actually imagine that while the solvent molecules leave the pore that a lot of phenomena may occure that can lead to the material collapsing. First of all MOFs usually need a highly polar solvent like DMF DEF or DMSO. All this solvents have a high boiling point. Also they tend to coordinate on the metal cluster. It is very tricky to evacuate a solid. One cource of action is to exchange the solvent with a volatile one. MeOh, CHCl3, CH2Cl2, Acetone or THF have been used for that reason in MOF evacuating. Then It can be evacuated with vaccuum. BUT usually vacuum is not enough. Keeping in mind the thermal stability of the material that may be found from TG experiments you might need to apply heating. Other ways involve CO2 supercritical point drying or CO2 gas flow. BUT usually MOFs collapse after solvent removal. Even if you manage to evacuate it water or air might contribut to it collapsing. Either way you have to monitor stability at all points preferentally by XRD before mounting it on the apparatus. That is you have to check if it remains crystalline after synthesis, after solvent exchange. After that if your Surface area is plausible that is if it is close to the surface area you are expecting then you are ok. Other wise if the material has partially collapsed you might still get a surface area but a smaller one . In that case you will have to change your cource of action. 

I hope this helps ... Keep well

Vacuum drying sis OK, But you need to check whether MOF struture is retained or not after solvent removal. Structural changes will certialy affect surface area.

hello.  i am synthesisn uio MOF for adsorption.  in condision of synthesis told after washing i should put (evacuated in vaccun in 150 0c  for 12 hour).  i have problem. how i creating vaccum?  by what apparatus?   vaccum oven?  freeze dryer?  evaporator?

Hi, you can use a vacuum oven if it is available.