Angular 7 - *ngIf on div to use class

I have the following div on my angular project:

<div *ngIf="isPreviewExpanded" class="project-daypart-group-columns-container-expanded pull-left">

Where I have two options: isPreviewExpanded can be true or false

if it's true I want to show it as it right now but if it's false I need to show like this:

<div *ngIf="!isPreviewExpanded" class="project-daypart-group-columns-container-collapsed pull-left">

The class changes within the value of isPreviewExpanded

I'm not being able to find any way to do that in the same div, something like:

<div *ngIf="isPreviewExpanded" class="project-daypart-group-columns-container-expanded; else class='project-daypart-group-columns-container-collapsed'>

Any ideas?